Quantum Computing · Diting Lab

High-fidelity universal quantum gates in a cryogenic atom array

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High-Fidelity Universal Quantum Gates in a Cryogenic Atom Array arXiv · Oct 30, 2026This paper demonstrates a universal quantum gate set in a cryogenic cesium-133 atom array. Single-qubit gates reach 99.970(2)% fidelity and raw two-qubit entangling gates reach 99.76(8)%, within the range of leading room-temperature implementations. The entangling gate uses direct single-photon coupling to a Rydberg P state, avoiding the scattering and light shifts of two-photon coupling. ★★★★ Notable: The authors demonstrate a universal gate set in a cryogenic cesium atom array, using direct single-photon Rydberg coupling for entangling gates, and report single-qubit fidelity of 99.970(2)% and raw

Testing logical Pauli measurements on a trapped-ion computer using QLDPC surgery

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Individually Addressed Logical Pauli Measurements by QLDPC Surgery on a Trapped Ion Quantum Computer arXiv · Oct 29, 2026The summary in this language did not pass the date and amount checks, so it is withheld. Check the original.

Algebraic strong-to-weak symmetry breaking and partial decodability in the surface code

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Algebraic strong-to-weak symmetry breaking and partial decodability in the surface code arXiv · Oct 30, 2026This paper studies how coherent noise produces unusual regimes of quantum error recovery and mixed-state order. It links a triangular-lattice surface code under single-qubit Z rotations with a Z2 paramagnet under strongly symmetric decoherence through Wegner duality. Increasing the rotation angle leads to a partially decodable critical phase in the code and an algebraic Z2 strong-to-weak symmetry breaking phase in the dual model. The authors derive universal observables using a weakly coupled SO(n) sigma model in the replica limit n→1, and large-scale simulations confirm these predictions. ★★★★ Notable: The authors link surface-code decoding and strong-to-weak symmetry breaking via Wegner duality, proposing an algebraic SWSSB phase with universal power-law and fidelity predictions checked numerically

Static dipolar impurity in a Fermi gas

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Static dipolar impurity in a Fermi gas arXiv · Oct 30, 2026This paper studies a static dipolar impurity immersed in a Fermi gas, examining how dipolar interactions shape few-body scattering and the resulting polaron physics. Using Fumi's theorem, the authors link anisotropic phase shifts directly to the ground-state energy and compute the exact impurity spectrum with a functional determinant approach. The spectrum is a convolution of independent even- and odd-wave contributions, yielding a ground state with both even- and odd-wave bound states occupied, whose separation is tunable via the dipole length. ★★★★ Notable: The authors apply Fumi's theorem and functional determinants to a dipolar impurity, reporting a doubly occupied ground state that a one-excitation variational ansatz misses.

Local determination of low-energy states in weakly interacting gapped fermion systems

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Local determination of low-energy states in gapped fermion systems with weak long-range interactions arXiv · Oct 30, 2026This paper studies gapped fermion systems obtained by adding sufficiently weak even many-body interactions to a free Hamiltonian with a spectral gap. It proves that if another interaction matches the bulk interaction inside a region U, its low-energy states in the range [0, 3g/4] have local expectations close to the bulk ground state deep inside U, with errors decaying with distance from the complement of U. The results imply, among other things, that the bulk interaction has a unique algebraic ground state. ★★★★ Notable: The authors prove quantitative local determination of low-energy states in gapped fermion systems with weak long-range interactions, yielding uniqueness of the algebraic ground state and localization

Stability of the bulk gap and spectral flow for fermions with weak long-range interactions

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Bulk gap stability and spectral flow for fermions with weak long-range interactions arXiv · Oct 30, 2026The paper proves that weak long-range many-body interactions preserve the bulk gap of a free fermion system. It constructs a quasi-local spectral flow that maps the free ground state to ground states of the interacting system. The results hold under polynomial decay conditions on the coefficients and interactions. ★★★★★ Notable: The authors prove bulk gap stability and construct a quasi-local spectral flow under weak long-range interactions, with polynomial decay conditions.

Three-dimensional quantum cellular automata that cannot be stabilized into circuits

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Three-dimensional QCA that are not stably circuits arXiv · Oct 30, 2026The paper proves that for every odd prime p, the three-dimensional chiral Z_p Clifford quantum cellular automata of Haah and of Sun, Yang, Wang, Tantivasadakarn and Chen are not finite-depth quantum circuits, even after tensoring with arbitrary ancillary degrees of freedom and composing with translations. Previously such results were known only within the Clifford category. As a consequence, the group of three-dimensional QCA modulo stabilized circuits and translations is not finitely generated. ★★★★ Notable: The authors introduce a new invariant for invertible subalgebras, proving 3D QCA are not finite-depth circuits beyond the Clifford setting; one key claim remains conjectural.

Why the Petz transpose map is the unique quantum analogue of Bayes' rule

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Inevitability of the Petz transpose map arXiv · Oct 29, 2026The paper asks whether quantum theory has a general retrodiction rule analogous to classical Bayes' rule, and whether such a rule is unique. The authors prove that a retrodiction assignment that is involutive, respects sequential and parallel composition, and agrees with unitary inversion must coincide with the Petz transpose map. The result applies to channels between finite-dimensional full matrix algebras. ★★★★ Notable: The authors prove Petz transpose map is uniquely forced by consistency axioms, axiomatically characterizing quantum Bayes' rule and a family of doubly rotated maps.

Experimental study of a reversible light-induced attack on quantum key distribution transmitters

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Reversible photorefractive attack in continuous-variable quantum key distribution arXiv · Oct 29, 2026This paper experimentally studies a reversible photorefractive attack on a continuous-variable quantum key distribution system. Moderate blue-light illumination lowers the modulation variance of a lithium-niobate IQ modulator to a stable value, and the variance recovers once the light is removed. The authors exploit this recovery to compromise modulation calibration, which leads to overestimated channel transmittance and underestimated excess noise. Key rates computed from the measured parameters can be positive when the correctly calibrated rate is nonpositive. ★★★★★ Notable: The authors report a reversible photorefractive attack that exploits recovery to miscalibrate modulation in CV-QKD, turning a nonpositive key rate positive.

Non-asymptotic bounds for quantum hypothesis testing via the Nussbaum-Szkoła mapping

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Non-Asymptotic Bounds via the Nussbaum-Szkola Mapping for Quantum Hypothesis Testing arXiv · Oct 29, 2026This paper studies quantum hypothesis testing, which distinguishes between quantum states. Using the Nussbaum-Szkoła mapping, the authors propose new lower and upper bounds for asymmetric quantum hypothesis testing. These bounds unify converse and achievability results across large-, moderate-, and small-deviation regimes. Numerical comparisons indicate that they approximate the optimal quantum error trade-off function more accurately at small blocklengths. ★★★★ Notable: The authors derive unified non-asymptotic lower and upper bounds via the Nussbaum-Szkoła mapping, with numerical comparisons against existing bounds.

Optimal Linear Combination of Hamiltonian Simulation for Simulating Dissipative Quantum Dynamics

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Optimal Linear Combination of Hamiltonian Simulation for Dissipative Dynamics arXiv · Oct 29, 2026Linear combination of Hamiltonian simulation (LCHS) is an efficient quantum-computing method for simulating dissipative dynamics, and its cost depends on the choice of kernel. The paper proves that the kernel family proposed by Ni and Ying minimizes LCHS query cost in the minimax sense. For target accuracy ε, the minimum cost is asymptotically (2e/π)(ln(1/ε) − ln ln(1/ε) + o(1)), with optimal leading constant 2e/π. The lower-bound proof combines weak duality with a realization lemma. ★★★★ Notable: The authors prove the Ni-Ying LCHS kernel family is minimax optimal, with leading constant 2e/π, via weak duality and a realization lemma.

Composable device-independent quantum digital signatures for verifying message integrity and authenticity

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Composable Device-Independent Quantum Digital Signatures arXiv · Oct 29, 2026This paper establishes a composable security framework for quantum digital signatures within constructive cryptography. It presents a device-independent protocol using one-time universal hashing and multi-channel multiplexing. The authors also derive a related-key security bound for LFSR-based Toeplitz authentication, and numerical simulations indicate efficient signing of multibit documents over metropolitan distances. ★★★★ Notable: The authors build the first composable security framework for QDS, propose a DI-QDS protocol, derive a related-key bound for LFSR-based Toeplitz authentication, and report finite-size simulations.

Quantum processes without definite causal order: a limit on how distinguishable and how precisely measurable their outputs can be

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Geometric Rényi divergence and RLD Fisher information under quantum processes without definite causal order arXiv · Oct 29, 2026The paper studies quantum processes without a definite causal order and proves that the geometric Rényi divergence at the output of a deterministic completely positive process cannot exceed the sum of the divergences of its individual channel uses. It also proves an additive bound on the RLD Fisher information of parameter-dependent channels, which yields a Cramér–Rao bound on locally unbiased estimation precision. An erasure-probability example attains this bound. ★★★★ Notable: The authors extend additive divergence and RLD Fisher information bounds to processes without definite causal order, proving a tight bound, an attaining example, and a Cramér-Rao consequence.

High-threshold fusion-based quantum computing with optical hybrid qubits

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High-Threshold Fusion-Based Quantum Computation with Optical Hybrid Qubits arXiv · Oct 29, 2026This paper proposes hybrid fusion-based quantum computation using small optical resource states that combine discrete- and continuous-variable encodings, connected through hybrid fusions. The authors present methods to generate these resource states directly, without local hybrid logic gates, and a decoding strategy that uses error information from individual fusion outcomes. They report a photon loss threshold of 2.231% using 12 hybrid fusions per surface-code unit cell, improving on a previous hybrid measurement-based scheme with a 0.89% threshold and 60 fusions. ★★★★ Notable: The authors report a hybrid DV-CV fusion-based scheme with a 2.231% loss threshold and 12 fusions per unit cell.

From entanglement bootstrap to DHR theory: linking anyon descriptions

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From Entanglement Bootstrap to DHR Theory arXiv · Oct 29, 2026This paper directly connects the entanglement bootstrap with the Doplicher–Haag–Roberts theory of superselection sectors for two-dimensional quantum spin systems. Under the entanglement-bootstrap assumptions, it proves Haag duality and shows a one-to-one correspondence between simple entanglement-bootstrap anyon types and irreducible superselection sectors. For each fusion channel, it constructs an affine bijection between density matrices on the fusion space and normalized positive intertwiners in the operator-algebraic channel. ★★★★ Notable: The authors link entanglement bootstrap to DHR superselection theory, proving Haag duality and a one-to-one anyon-sector correspondence.

Classical communication over quantum channels: does entanglement help?

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Classical communication over quantum channels: does entanglement help in nature? arXiv · Oct 30, 2026This paper examines whether entangling codewords across independent uses of a quantum channel can increase the rate of classical communication. The authors propose a general Schur-weighted block entropy inequality. They show that phase-covariant channels, including multi-level amplitude damping, generalized dephasing, and damping-dephasing channels, have no entanglement advantage. The result also recovers the known conclusion for all qubit channels. ★★★★ Notable: The authors propose a Schur-weighted block entropy inequality and show no entanglement advantage for phase-covariant channels, recovering the qubit result.

What Can Be Computed with Indefinite Causal Structure? A study of whether quantum computing gains power when operations lack a fixed causal order.

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What Can Be Computed with Indefinite Causal Structure? arXiv · Oct 30, 2026The paper studies whether quantum computation becomes more powerful when operations need not follow a definite causal order, using the process matrix formalism of Oreshkov et al. The authors give polynomial-time algorithms in two settings. General process matrices can solve every problem in NP, using valid processes that satisfy the purification postulate and generate unitary channels. Requiring the process matrices to be pure, they solve unique-sink orientation in polynomial time, which suggests indefinite causal order can exceed BQP while preserving unitarity. ★★★★★ Notable: The authors show indefinite causal order yields computational power beyond BQP, solving NP problems and unique-sink orientation in polynomial time within the process matrix formalism.

On the Quantum Chromatic Gap II: a proof of a strong form of pseudo-telepathy

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On the Quantum Chromatic Gap II arXiv · Oct 30, 2026This paper confirms a conjecture from the first author's SODA'26 paper about Khot's d-to-1 games. It constructs label-cover games with classical value below any given epsilon that still admit a perfect quantum strategy. As a consequence, there are graphs with quantum chromatic number 3 and arbitrarily large classical chromatic number, the first improvement on this gap since Brassard, Cleve, and Tapp. ★★★★ Notable: The authors construct graphs with quantum chromatic number 3 and arbitrarily large classical chromatic number, improving on prior exponential gap results.

Fast, accurate neural decoding for ultra-high-rate quantum error-correcting codes

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Fast and accurate neural triage decoding of ultra-high-rate quantum LDPC codes arXiv · Oct 30, 2026This paper introduces neural triage decoding, a framework that uses syndrome consistency to adaptively allocate neural computation for decoding quantum error-correction codes. A local neural message-passing network quickly predicts corrections, extra iterations reduce residual syndrome violations, and a rarely used diversification stage searches for consistent corrections for the remaining cases. The authors demonstrate the Triage decoder on ultra-high-rate quantum LDPC codes encoding a few hundred logical qubits, including lifted-product and Kasai codes, reporting accuracy comparable to near-optimal algorithmic decoders with latency reduced by roughly one to two orders of magnitude. ★★★★ Notable: The authors propose a syndrome-consistency-guided neural decoder, reporting near-optimal accuracy with substantially lower latency on high-rate qLDPC codes.

Adaptive local measurements can beat fixed global measurements exponentially in quantum learning

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Adaptive Local Measurements For Quantum Learning Can Exponentially Outperform Nonadaptive Global Measurements arXiv · Oct 29, 2026This paper asks whether measurements chosen adaptively, based on earlier outcomes, can be exponentially more informative than measurements fixed in advance. The authors construct multi-qubit states that encode a scalar parameter in one of exponentially many candidate observables, indicated by an auxiliary marker. An adaptive protocol using only single-qubit measurements and one round of adaptation needs logarithmically many copies, while every nonadaptive protocol needs exponentially many. The gap arises from measurement incompatibility, and the states are separable. ★★★★ Notable: The authors show that adaptive single-copy local measurements achieve an exponential advantage over nonadaptive global measurements, with tight bounds up to the exponential base.

Local quantum fault tolerance without expansion arguments

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Local Quantum Fault Tolerance Without Expansion arXiv · Oct 29, 2026This paper studies fault-tolerant quantum computation using a fixed local error-correction rule and the cubical (d,d')-Toric code, including the 4D Toric code. Under sufficiently weak local-stochastic Pauli noise, the correction cycle acts only on the current syndrome, has constant depth, and needs no multiscale decoder or scale-dependent delays. The authors give a local higher-dimensional sweep rule, prove a circuit-level threshold theorem for noisy sweep cycles interleaved with logical gates, and bound the probability of ideal decoding under local-stochastic noise. ★★★★ Notable: The authors give a local higher-dimensional sweep rule and a circuit-level threshold theorem without expansion, covering the 4D Toric code.

Recovering hidden conserved densities in quantum simulators from snapshot measurements

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Reconstructing hidden observables via quantum snapshot thermometry arXiv · Oct 30, 2026Projective snapshots on quantum simulators directly probe only observables diagonal in the measurement basis. The paper combines local equilibration with an independently calibrated equilibrium equation of state to reveal hidden conserved-density profiles. Numerical demonstrations show recovery of energy fronts and a diffusion constant, and separation of spin transport from energy spreading.

Renormalization for stable memory from independent local updates without synchronization

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Renormalization for Robust Memory without Synchronization arXiv · Oct 30, 2026The paper develops a spacetime renormalization framework showing how independently acting local updates can collectively preserve classical information when sites evolve at random, unsynchronized times. It gives sufficient conditions under which stable interfaces and suppressed defect propagation yield reliable erosion at large scales. Applying this, the authors prove stability of an asynchronous R squeezing code and introduce robust processes in two and three dimensions, where both encoded phases persist under sufficiently weak noise.

Comparing entangling strategies for unitary synthesis, a study of how multiqubit gates on trapped-ion computers perform in building target quantum operations.

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Comparison of entangling strategies for unitary synthesis arXiv · Oct 30, 2026This paper examines whether multiqubit gates on trapped-ion quantum computers are worth their added engineering complexity. The authors use unitary synthesis, a task not tied to any specific application, as a benchmark for gate sets built from native Mølmer–Sørensen multiqubit gates. They also develop a toolset for evaluating such gate sets and identify the hardware requirements under which multiqubit gates become advantageous.

Entanglement diagnostics in stochastic-resetting steady states, tested on superconducting qubits

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Entanglement diagnostics of stochastic-resetting steady states: theory and measurement on superconducting qubits arXiv · Oct 30, 2026The paper studies entanglement in nonequilibrium steady states of the transverse-field Ising chain under stochastic resetting, giving closed-form results for two qubits and exact calculations for chains up to 12 qubits. Measurements on an IBM superconducting processor show averaged entropies closely matching noiseless predictions, while concurrence mostly falls below prediction, captured by a depolarizing model with one fitted parameter. The difference between the two entropies, the Jensen gap, equals the Holevo information a subsystem retains about the time since the last reset, which grows with chain length.

Locality in Dissipative Ground-State Preparation: Whether Local Dissipation Can Prepare a Local Hamiltonian's Ground State

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Locality in Dissipative Ground-State Preparation arXiv · Oct 30, 2026This paper asks whether the ground state of a free-fermion Hamiltonian can be prepared using local dissipation. The authors use a quadratic Lindbladian with linear jump operators and link spatial locality to momentum-space analyticity via Fourier correspondence. They derive a complete spectral criterion for exponentially local jump operators that prepare the ground state. The results show that sign-changing Fermi-level crossings rule out such preparation in one dimension, while additional obstructions arise in higher dimensions.

Left-handed transmission lines for generating photons via the dynamical Casimir effect

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Left-Handed Transmission Lines for the Dynamical Casimir Effect arXiv · Oct 30, 2026This paper studies superconducting transmission lines built with series capacitors and shunt inductors, terminated by a flux-modulated SQUID. The authors derive the quantum Hamiltonian and compare the line with a right-handed line and a coplanar waveguide built from the same elements. With equal elements, the left-handed coupling exceeds the right-handed one above a crossover pump frequency, and the created particles stay in the target mode.

Optimal estimation of diamond distance between unitary channels

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Optimal Diamond Distance Estimation for Unitary Channels arXiv · Oct 30, 2026This paper presents a quantum algorithm that estimates the diamond distance between two unknown d-dimensional unitary channels to within additive error ε. It uses O(√d/ε) queries to the unitary channels and their inverses. The query complexity matches the lower bound due to Jeon and Oh (npj Quantum Inf., 2026), so the algorithm is optimal.

Using Exceptional Points to Detect Non-Gaussian Noise

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Exceptional Points as Witnesses of Non-Gaussian Noise arXiv · Oct 30, 2026The paper shows that exceptional points (EPs) in the noise-averaged dephasing response of quantum devices can reveal non-Gaussian noise statistics that the power spectrum alone cannot distinguish. It introduces a model describing dephasing environments as identical independent noise sources while preserving the power spectrum. Given a calibrated single-source model, the largest EP order extracted from the measured response determines the number of sources and predicts higher-order statistics of the combined noise.

Algebraic theory of abelian fractons: fusion, mobility and statistics in gapped fracton phases

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Algebraic theory of abelian fractons and beyond arXiv · Oct 30, 2026This paper develops an algebraic framework for fusion, mobility and statistics in abelian gapped fracton orders and topological phases, generalizing the algebraic description of abelian anyons to systems with restricted mobility and extended excitations. It introduces braided fusion complexes, which encode fusion, mobility and statistics, and defines braided fusion theories as their equivalence classes. The authors also study mutual statistics and remote detection for nondegenerate theories, and prove that the excitation-detector principle is equivalent to nondegeneracy under a unique infinite-space ground state assumption.

Optimal detuning and gate time for strong single-qubit gates beyond the rotating-wave approximation

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Optimal detuning and gate time for strongly driven single-qubit gates beyond the rotating-wave approximation arXiv · Oct 30, 2026This paper studies how single-qubit quantum gates lose accuracy when strong driving is used, since the rotating-wave approximation no longer holds. The authors analyse the error using an effective Magnus-Taylor Hamiltonian through second order in the inverse driving frequency. They correct the driving frequency with an amplitude-dependent Bloch-Siegert-type shift and rescale the gate time to restore the RWA gate conditions. Numerical solutions of the Schrödinger equation show that these corrections reduce gate infidelity by several orders of magnitude, widening the usable range of driving amplitudes.

Probing photon emission fluctuations in spin-injected quantum dots using time-dependent electrical excitation

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Probing fluctuations in photon emission statistics of spin injected quantum dots with time dependent electronic excitation arXiv · Oct 30, 2026This paper studies electrically spin-injected InGaAs/GaAs quantum dot ensembles that emit circularly polarized single photons without an external pump laser. Using an extended Hanbury Brown-Twiss interferometer with four detectors, the authors measure time-resolved photon-number statistics and find that two-photon statistics fluctuate at several points within each excitation pulse. These fluctuations disappear when the spin-injection layer is demagnetized, linking multi-photon emission dynamics to the spin polarization of injected carriers.

Nested toric codes: decoupling translation-invariant topological CSS codes in higher dimensions

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Toric codes all the way down: decoupling translation-invariant topological CSS codes in higher dimensions arXiv · Oct 30, 2026This paper studies topological CSS quantum error-correcting codes in three or more spatial dimensions, which are useful for fault-tolerant quantum computation. The authors show that such a code can be decoupled into a stack of higher-form toric codes by a finite-depth local Clifford circuit once, after coarse-graining to a superlattice, translations act trivially on each excitation layer and the gluing between layers vanishes. They also give an explicit algorithm that builds this decoupling circuit from SUM and SWAP gates.

Grow, Compress, and Perturb: A Hybrid Quantum-Classical Method for Scalable Quantum Chemistry

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Grow, Compress, and Perturb: A Hybrid Quantum-Classical Pathway to Scalable Quantum Chemistry on Quantum Computers arXiv · Oct 30, 2026This paper introduces VULCAN, a layered variational quantum eigensolver framework that avoids Hamiltonian gradient measurements by building ansatz operators dynamically with variational double bracket flow. Emulations on up to 32 logical qubits reach chemical accuracy for hydrogen chains, BeH2, and H2O using 5-20% of the measurement cost of batched ADAPT-VQE. For the 32-qubit C3H6 case, a single VULCAN layer combined with a GPU-accelerated stochastic ENPT2 correction reaches chemical accuracy, where batched ADAPT-VQE does not.

Quasi-Phases of Quantum Matter: Distinct Gapped Regimes Near a Critical Point

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Quasi-Phases of Quantum Matter arXiv · Oct 30, 2026The paper introduces quasi-phases, gapped regimes near a critical point that are connected in the broader phase diagram but not by any gapped path reachable through small perturbations of the critical theory. In spin-chain examples with central charge c=1, the authors identify multicritical c=3/2 and c=9/5 orbifolds that describe these quasi-phases. The work also argues that such quasi-phases can carry interface modes with higher-dimensional linear representations.

Gauge-invariant orbital angular momentum of vector optical vortices beyond the paraxial approximation

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On the gauge-invariant orbital angular momentum of vector optical vortices in the paraxial approximation and beyond arXiv · Oct 30, 2026This paper presents a gauge-invariant formalism for describing the spin and orbital angular momenta of scalar and vector optical vortices. A correction term arising from consistent treatment of the transverse vector potential's nonlocality restores gauge invariance and allows the total angular momentum to be separated into spin and orbital parts. The authors show that the orbital angular momentum of multimode vector vortex beams has two qualitatively different components and discuss the limits of applicability of the formalism.

Benchmarking fast quantum annealing with domain walls

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Using domain walls to benchmark fast quantum anneals arXiv · Oct 30, 2026This paper studies the distribution of domain walls in ground states of frustrated one-dimensional Ising spin chains with anti-parallel boundary spins. Ideal chains are expected to show a sine-squared distribution quantumly and a uniform distribution classically, while chains with random imperfections on a physical device show a U-shaped profile. Using D-Wave's fast anneal feature, the authors observe a sine-squared distribution consistent with coherent quantum behavior and propose the extent of the domain wall distribution tail as a platform-independent metric.

Lattice moments and quantum designs

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Lattice moments and quantum designs arXiv · Oct 30, 2026The paper shows that the ensemble of unimodular Gottesman-Kitaev-Preskill distributions does not form a rigged quantum 3-design. It quantifies the replica defect responsible for this failure. The result is established by rederiving a second moment formula for symplectic lattices in a self-contained way.

Entropic fluctuations in quantum statistical mechanics: a review of how classical entropy fluctuation theorems are extended to quantum systems.

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Entropic Fluctuations in Quantum Statistical Mechanics: A Review arXiv · Oct 30, 2026This paper reviews and compares several ways the Evans-Searles and Gallavotti-Cohen fluctuation theorems for entropy production can be extended to quantum systems. It introduces a recent approach and adds an extension of the steady-state version to two-time measurement entropy production in the algebraic setting. The authors discuss open quantum systems, the connection to modular theory, and a quantum principle of regular entropic fluctuations. They also relate these entropy production statistics to spectral resonances of quantum transfer operators, applied to the spin-fermion model.

Spectral metrics inspired by quantum walks for judging QAOA mixer choices

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Quantum-Walk Inspired Spectral Metrics for Evaluating QAOA Mixers arXiv · Oct 30, 2026Inspired by quantum-walk mixing theory, the paper proposes two spectral indicators for QAOA mixer topologies: the normalized minimum eigenvalue separation of the mixer Hamiltonian, and the long-time averaged minimum eigenvalue separation of the mixer unitary. The authors derive exact expressions and asymptotic bounds for the complete graph, hypercube, cycle, and balanced 2-D torus. For random permutation-invariant cost Hamiltonians the spectral ordering broadly matches observed QAOA performance, but for structured 1-D and 2-D Ising QUBOs it breaks down, suggesting mixer-cost alignment matters.

Sharpening particle trajectories by changing quantum reference frames

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Trajectory sharpening under quantum reference frame transformations arXiv · Oct 30, 2026This paper links quantum reference frame transformations to experimental effects. Using a toy model of free particles with signed masses, it shows that trajectory sharpening from correlating a system with a negative-mass reference can be read as a transformation to a negative-mass frame. The authors define frame-invariant sharpness measures and derive monogamy relations limiting sharpness with respect to two negative-mass frames.

Process matrices for generalised physical theories, extending indefinite causal order beyond quantum theory.

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Process matrices on generalised theories arXiv · Oct 30, 2026The paper extends the process-matrix framework for indefinite causal orders to a broad class of generalised physical theories. It re-axiomatises spacetime contexts through naturality over classical probes, capturing non-contextual assignment with compatibility for convexity and coarse-graining. It characterises which theories admit a process-matrix representation of abstract spacetime contexts, and identifies when supermap and process-matrix perspectives coincide in classical, quantum, and Boxworld-like theories.

A universal gauge structure in the photon content of light-matter systems

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A universal gauge structure in the photon content of light-matter systems arXiv · Oct 30, 2026After truncating the matter space of single-mode light-matter models, gauge changes leave the spectrum unchanged but alter the ground-state photon number, whose meaning has been disputed. The paper shows that when the gauge transformation is a field displacement coupled to a matter operator, this photon number is an exact quadratic polynomial in the gauge parameter. Its minimum over all gauges is gauge-invariant and, for the quantum Rabi model, is set by the ground-state energy alone.

Structural limits of QAOA mixer design: transport and causal reach

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Structural Bottlenecks in QAOA Mixer Design: Transport and Causal Reach arXiv · Oct 30, 2026The paper examines mixer design in the Quantum Approximate Optimization Algorithm (QAOA), identifying two structural bottlenecks for shallow circuits: probability transport across configuration space and finite-depth causal reach. It derives mixer-dependent first-order objective bounds and a non-perturbative spreading condition. For MaxCut, it adds problem-graph-aligned two-local interactions to the transverse-field mixer, and reports that X+XX and X+YY improve approximation ratios over the standard X mixer at equal depth.

Electric field control of spin transport anisotropy in a layered antiferromagnet

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Electric field control of anisotropic spin traffic between spin-filtering and magnon-scattering in a layered antiferromagnet arXiv · Oct 30, 2026This paper studies a dual-gate field-effect transistor built on CrSBr, a layered A-type antiferromagnetic semiconductor. The measurements show that the displacement field, rather than carrier doping, mainly determines the sign and magnitude of the magnetoresistance ratio. The authors explain the effect using ab initio calculations and an effective spin-circuit model. They conclude that the displacement field is an efficient electrical knob for controlling spin transport in CrSBr.

Micromagnetic Lagrangian and Hamiltonian formulation of magnon-photon coupling in cavities

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Micromagnetic Lagrangian and Hamiltonian Normal-Mode Formulation of Cavity Magnon-Photon Interactions arXiv · Oct 30, 2026This paper studies how magnons and photons interact inside a resonant microwave cavity, starting from linearized Maxwell and Landau-Lifshitz equations. The authors introduce an electric vector potential and an interaction Lagrangian, expand fields in normal modes, and derive a Hamiltonian using the Faddeev-Jackiw approach. A generalized Bogoliubov transformation then diagonalizes the coupled system into polariton variables. As an example, a perpendicularly magnetized YIG disk in a rectangular cavity shows hybridization of the cavity mode with several magnetostatic modes and frequency shifts near conducting walls.

Fault-tolerant Heisenberg-limited quantum sensing using bosonic probes

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Fault-Tolerant Heisenberg-Limited Quantum Metrology with Bosonic Probes arXiv · Oct 30, 2026This paper proposes a fault-tolerant protocol that uses bosonic probes to estimate displacements in the presence of dephasing noise. The authors construct an optimal error-correcting code under a mean photon-number constraint, with a repetition-encoded qubit register and repeated boson-parity measurements. Under circuit-level bit-flip noise, a distance-d code suppresses logical failures to order p^((d+1)/2). The Fisher information scales as NT² over interrogation times of order γ_A^(-(d+1)/2), compared with γ_A^(-1) for the non-fault-tolerant approach.

Classifying cavity-modified reaction types via linear free-energy relationships

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Characterizing Reaction Types through Linear Free-Energy Relationships in Cavities arXiv · Oct 30, 2026This paper extends nonempirical linear free-energy relationships to reactions inside optical cavities and finds that they fall into four reaction types set by simple response-crossing rules. Reactions may follow conventional Bell-Evans-Polanyi (BEP) or counterintuitive Opposite-BEP behavior, or switch between them as cavity frequency changes. The framework is demonstrated in the Shin-Metiu model and four molecular reactions, and the complexity is reduced to competition between permanent-dipole and polarizability responses.

Quantum computing via computational imaging: representation, measurement, and inference

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Quantum Computing through Computational Imaging: Representations, Measurement, and Inference arXiv · Oct 30, 2026This paper, aimed at computational-imaging and engineering readers, examines how the representation, measurement, and decoding of a quantum state determine what information can be returned. It distinguishes amplitude encodings of input values from encodings of complete candidate labelings, and studies unknown-phase inference under complex-field interference. It links singular-value decomposition of reshaped joint amplitudes to pure-state entanglement. In a four-pixel segmentation example, one QAOA layer lowers mean energy relative to uniform sampling yet makes a nonoptimal labeling more probable than the optimum.

Fast mixing of Gibbs samplers for quantum spin systems with all-to-all coupling

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Rapid mixing for Gibbs samplers for quantum spin systems with all-to-all interactions arXiv · Oct 30, 2026This paper studies how quickly Gibbs states of two-local quantum Hamiltonians on arbitrary interaction graphs, including fully connected systems, can be prepared using Lindblad dynamics satisfying KMS detailed balance. The authors adapt the classical Dobrushin condition to the quantum setting and use the order-1 quantum Wasserstein distance to measure how local perturbations spread. In a high-temperature regime set by the maximum total interaction strength per site, they derive contraction estimates that yield mixing times logarithmic in system size and inverse error tolerance.

Subsystem Spacetime Code: A Quantum Error-Correction Framework for Measuring Clifford Circuit Fault Distance

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Subsystem Spacetime Code arXiv · Oct 30, 2026The paper constructs a subsystem spacetime code and uses it to characterize the distances of Clifford circuits. Its gauge group can be explicitly constructed and classified using masking properties of instantaneous stabilizer groups, and consists of faults that are harmless to the circuit. The framework is also used to identify where a dynamical code loses distance and to analyze how fault distance changes when circuits are composed from smaller components.

Multidimensional Revival Dynamics in a Bosonic Many-Body System: A study of how localized quantum states collapse and revive in a two-site Bose-Hubbard model

2026-10-30T00:00:00+09:00

Multidimensional revival dynamics in a bosonic many-body system arXiv · Oct 30, 2026This paper studies quantum interference in a symmetric two-site Bose-Hubbard model. Starting from a coherent state prepared on one site in the strongly self-trapping regime, the authors derive revival behaviors in expectation values, coherences, and the autocorrelation function, and illustrate the entanglement behavior. They identify several new features and show that a comprehensive semiclassical theory explains them, with excellent agreement to quantitative comparisons.

QDMin: Quantum Search for Energy Minima in Nuclear Shape Landscapes

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QDMin: Coherent Quantum Minimum Finding for Nuclear Deformation Landscapes arXiv · Oct 30, 2026This paper presents QDMin, a method for locating the minimum of a nuclear collective energy landscape. It searches a parameterized Hamiltonian family using a coherent collective-coordinate register and an on-demand ground-energy threshold oracle, avoiding point-by-point construction of the landscape. The method is implemented for a schematic pairing-plus-multipole model, with calculations at four points and on a 4×4 quadrupole–octupole grid.

Transport in spinful non-Hermitian gauge lattices: spin-dependent skin effects and transmission in one-dimensional lattices with gauge fields

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Transport in spinful non-Hermitian gauge lattices arXiv · Oct 30, 2026This paper extends a generalized transfer-matrix method to one-dimensional non-Hermitian tight-binding lattices with spin and matrix-valued Abelian and non-Abelian gauge couplings. In the Abelian case the spin sectors separate, giving exact spectra and closed transport expressions with spin-dependent skin localization. In the non-Abelian case noncommuting couplings mix the spin sectors, producing spin-hybridized lasing, coherent perfect absorption, and direction-dependent reflectionless transport with spin conversion.

Upper bounds on general (r,δ) quantum locally recoverable codes

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Bounds for General (r,δ)-Quantum Locally Recoverable Codes arXiv · Oct 30, 2026This paper studies general (r,δ) quantum locally recoverable codes without assuming purity or stabilizer structure, allowing recovery blocks to overlap arbitrarily. It establishes a Singleton-like upper bound for general quantum subspaces and tightens it with an explicit remainder correction. The authors also extend a known pure-code parameter bound to arbitrary pure quantum subspaces and analyze three code families that attain these bounds.

Stabilizing fluctuating Cooper pairs using a terahertz resonator

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Stabilizing fluctuating Cooper pairs with a terahertz resonator arXiv · Oct 30, 2026This paper develops an equilibrium theory of a mesoscopic, disordered two-dimensional superconductor coupled to a subwavelength terahertz resonator, focusing on how superconducting phase fluctuations interact with the resonator's electromagnetic fluctuations. Modeling the resonator as a lumped-element circuit, the authors find that coupling raises the superconducting transition temperature Tc rather than suppressing it. For a 1 µm × 1 µm, 8 nm-thick disordered film, they estimate a relative Tc enhancement of about 1%, roughly ten times the 0.1% obtained when phase fluctuations are neglected.

Detuned cavity boosts spectroscopy precision for dipole moment estimation

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Detuning-assisted cavity enhancement in spectroscopy arXiv · Oct 29, 2026This paper studies cavity-enhanced spectroscopy with the cavity frequency deliberately detuned from the transition of interest. The authors report that detuning can improve dipole moment estimation precision by up to two orders of magnitude compared with resonant operation, including in the presence of losses. They attribute the gain to a detuning-controlled redistribution of information between light- and matter-like polaritons, and note it is accessible with conventional photodetection and time-correlated single-photon counting.

A density calculus for quantum field theory: an introduction to Haagerup L^p spaces

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A density calculus for quantum field theory arXiv · Oct 29, 2026These notes introduce Haagerup noncommutative L^p spaces for quantum field theorists, extending density matrix calculus to type III algebras where no intrinsic trace exists. The authors construct the spaces first for matrices, via crossed products and dual actions, then for general von Neumann algebras, discussing how normal states are represented by Haagerup densities. As an application, they compute the sandwiched Rényi divergence for a coherent excitation of a chiral current, checking monotonicity under restriction and the Rényi quantum null energy condition for all real orders α>1.

Estimating how alike two unknown continuous-variable quantum states are, across separate quantum platforms

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Distributed Inner-Product Estimation for Continuous-Variable Quantum States arXiv · Oct 29, 2026This paper proposes a CV-DIPE protocol that estimates the inner product between two unknown quantum states prepared on distributed platforms. It uses only local homodyne measurements at shared phase settings and classical communication. Under a known bound on mean energy per mode, the authors derive explicit finite-sample guarantees and sufficient copy counts for a prescribed accuracy and confidence. Numerical simulations with Gaussian and non-Gaussian states show the trade-off between truncation bias and statistical error.

A dissipative controller as a hidden source of quantum gate errors

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Dissipative controller as a hidden source of errors in quantum gates arXiv · Oct 29, 2026Quantum systems are usually controlled by classical devices that inevitably dissipate energy into their surroundings. Using the fluctuation-dissipation theorem, the paper studies how the noise in the control field relates to the entropy produced by the macroscopic controller, working with a minimal model. In the fast-control, high-fidelity regime, it finds a tradeoff between dissipation and control errors. Perturbative calculations of gate fidelity and of state-transfer fidelity via shortcuts to adiabaticity in the Landau-Zener model illustrate this tradeoff.

Identifying Executed Logical Operations from Syndrome Histories in qLDPC Codes

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Identifying Logical Operations from Syndrome Histories for qLDPC Codes arXiv · Oct 29, 2026This paper shows that syndrome histories, normally used for error correction in fault-tolerant quantum computation, can also reveal which logical operations were executed. The authors develop an exact inference method and a scalable approximation that account for unknown faults and measurement randomness. Evaluated on [[18,4,2]] and [[72,12,6]] bivariate bicycle codes, single logical instructions are identified with over 94% accuracy under circuit-level noise.

Non-Bloch dynamical quantum phase transitions in chains with memory

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Non-Bloch Dynamical Quantum Phase Transitions with Memory arXiv · Oct 29, 2026Dynamical quantum phase transitions in periodic chains are governed by real Bloch momenta. This paper identifies non-Bloch transitions that appear only in open chains and are governed by complex momenta, arising in a Hermitian chain coupled to a simple substrate with exactly treated memory. The effect stems from the point-gap winding number W of the projected propagator. For nonzero W, open boundaries alter both the dynamical free energy and critical times, even in the thermodynamic limit, and both follow from analytic continuation to complex momenta. The authors also show that W can be measured by particle counting.

Nonequilibrium thermodynamics of a small quantum system linked to quantum heat reservoirs

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Nonequilibrium statistical thermodynamics of a small quantum system coupled to quantum reservoirs arXiv · Oct 29, 2026This paper uses a statistical mechanical framework in which nonequilibrium averages of selected quantum observables are expressed exactly as averages over local density operators, to describe a small quantum system coupled to reservoirs. It focuses on how the system's average internal energy evolves, including under external autonomous driving that does work on it, and on entropy production within the system. When the system couples to large quantum reservoirs, its effect on them is captured by boundary conditions on the reservoir equations, which the authors derive. The framework is illustrated with heat transfer through a quantum system connected to two heat reservoirs at different temperatures.

Whether a quantum system's memory measures depend on its surrounding environment's state

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Bath-state (In)dependence of Non-Markovianity Measures in Quadratic Open Systems arXiv · Oct 29, 2026This paper studies a fermionic quadratic open quantum system. It shows that the Breuer-Laine-Piilo and Lorenzo-Plastina-Paternostro non-Markovianity measures are independent of the bath state. In contrast, the Rivas-Huelga-Plenio measures and the Megier-Smirne-Vacchini entropic measure remain sensitive to the reservoir's temperature and chemical potential.

Estimating Inner Products of Distributed Continuous-Variable Quantum States

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Distributed Inner Product Estimation of Continuous-Variable Quantum States arXiv · Oct 29, 2026This paper studies continuous-variable distributed inner product estimation (CV-DIPE), which compares unknown states prepared by distant bosonic and quantum optical systems without requiring efficient classical descriptions or joint measurements. The authors develop three protocols for energy-constrained continuous-variable states, based on coordinated displaced parity, coordinated Haar measurements, and independent homodyne shadows. For arbitrary multimode inputs, including entangled and non-Gaussian states, they establish truncation error bounds and worst-case sample complexity guarantees. The leading terms favor coordinated Haar measurements, which are experimentally challenging to implement globally.

Kelvin-wave multiplication through sound emission

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Kelvin-Wave Multiplication by Sound Emission arXiv · Oct 29, 2026The paper studies how a subsonic Kelvin quantum can emit a phonon and split into two lower-energy quanta, increasing Kelvin population while losing energy. In the soft-phonon limit, rotational invariance links the leading acoustic shear amplitude to the released energy, and microscopic calculations support this dispersion dependence. In a reflecting cavity with coherent sound and Kelvin seeds, Gross-Pitaevskii simulations show Kelvin gain, and shifting the initial sound phase by π reverses these changes.

Quantum neural network combining digital and analog operations using long-range interactions

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Digital-Analog Quantum Neural Network with Long-Range Interactions arXiv · Oct 29, 2026The paper proposes a digital-analog quantum neural network (DA-QNN) whose analog blocks use an Ising model with power-law long-range interactions to generate entanglement, reducing the number of two-qubit entangling gates. It is benchmarked on supervised and unsupervised learning tasks. For image classification and many-body phase detection, the long-range ansatz matches short-range performance with fewer layers or shorter evolution times. In unsupervised phase detection, the two ansatzes give complementary signatures that together reconstruct the full phase diagram.

Entropy-maximizing mixed quantum states with a fixed average

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Maximum-Entropy Ensemble of Quantum Subsystems with a Fixed Average State arXiv · Oct 29, 2026This paper studies the maximum-entropy distribution of mixed quantum states under a fixed ensemble average. Its eigenvalue density is argued to converge asymptotically to that of the correlated Wishart ensemble (CWE), obtained via a free multiplicative convolution formula. Applied to the transverse-field Ising model with a thermal average state, it yields a high-temperature correction to the Marchenko-Pastur law. The authors also show, with numerical support, that the ensemble after random POVM measurement is asymptotically equivalent to the CWE, and compute finite-temperature Page curves for average entanglement entropy.

Optimized dynamical decoupling for spin ensembles with large inhomogeneities

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Optimized Dynamical Decoupling for Spin Ensembles with Large Inhomogeneities arXiv · Oct 29, 2026This paper compares many dynamical decoupling (DD) protocols for protecting coherence and enabling quantum sensing in an ensemble of negatively charged NV centers in diamond under ambient conditions. The authors identify an optimal approach that uses rapid adiabatic passage pulses, which are robust to amplitude and frequency inhomogeneity, combined with varying their phases. Experiments show improved signal contrast and an order-of-magnitude longer memory time compared to XY8 with standard rectangular pulses, and the method is also applied to sensing a weak oscillating field.

Error-Corrected Quantum Optimization with Rydberg Atom Array Embeddings: Using Embedding Ancillary Atoms for Error Correction

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Error-Corrected Quantum Optimization via Rydberg Atom Array Embeddings arXiv · Oct 29, 2026This paper studies how Rydberg atom arrays solve combinatorial optimization on complex graphs through embeddings that add ancillary atoms. The authors show that the embedding structure naturally forms a classical error-correcting code and introduce a Cluster decoder to correct bit-flip errors. On the QuEra Aquila device, the decoder recovered exact optimization solutions with an average success rate of at least 8% for systems of up to 107 atoms.

A method for detecting and suppressing quantum decoherence caused by collisions with the environment.

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Detection and Inhibition of Decoherence Through Collisions: A dynamical approach arXiv · Oct 29, 2026The paper proposes two protocols for protecting quantum states from noise without needing full knowledge of the noise dynamics, based on a collisional model. The first preserves the states of qubits, and the second protects a logical qubit under similar conditions. According to the paper, the protocols protect arbitrary single-qubit and entangled states against general noise and scale to any number of qubits.

Probabilistic imaginary-time evolution using precompiled diagonal Hamiltonian representations

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Probabilistic imaginary-time evolution via compiled diagonal representations arXiv · Oct 29, 2026The paper proposes a probabilistic imaginary-time evolution method that uses a compiled approximate diagonal representation of the Hamiltonian, with the basis transformation optimized offline. For a fixed compiled representation, the online circuit structure and gate count per attempt do not depend on imaginary time, and the representation can be reused across input states and evolution times. The authors derive a condition for enhanced success probability and report numerical tests showing lower online cost than termwise Pauli-based methods at a common accuracy threshold. They also examine how approximation errors and offline preparation costs affect the overall benefit.

Sharp Tilting Inequalities: An Optimal Bound on the Directional Derivative of the Logarithm and Fractional Powers

2026-10-29T00:00:00+09:00

Sharp Tilting Inequalities arXiv · Oct 29, 2026This paper studies a trace inequality for positive semidefinite matrices A and B, involving the directional derivative of the logarithm and fractional powers, with parameter 1/2≤α≤1. The authors prove an upper bound with the optimal coefficient. The result extends to positive trace-class A and positive, possibly unbounded, self-adjoint B on a separable Hilbert space. The proof uses a superoperator representation of the logarithm's directional derivative and an Araki-type estimate for the derivative of a fractional power.

Training quantum algorithms with adiabatic methods to detect entanglement

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Adiabatic training of VQAs for entanglement detection arXiv · Oct 29, 2026This paper proposes a hybrid quantum framework that trains Variational Quantum Algorithms with an adiabatic-inspired optimization strategy to detect entanglement. The method combines parameter-space discretization with a hierarchical segmentation scheme and formulates the problem as a QUBO model for quantum annealing. Preliminary results are compared against classical neural networks and conventional VQA training techniques.

Pöschl-Teller-type Jaynes-Cummings Hamiltonians via supersymmetric transformations

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Pöschl-Teller type of Jaynes-Cummings Hamiltonians: SUSY transformations arXiv · Oct 29, 2026This paper uses supersymmetric quantum mechanics to define and study generalized Jaynes-Cummings (JC) Hamiltonians. Trigonometric and hyperbolic Pöschl-Teller potentials are used to modify the standard JC model. The generalized Hamiltonians share several features with the standard JC model, including matrix intertwining, excitation number symmetry, Rabi frequency, atomic inversion formulas, and classical and revival times. The authors conclude that the JC Hamiltonian is one example of a wider class of generalized Hamiltonians.

Conditional Information Flow in Rotated Cluster States and Neural Learnability

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Conditional Information Flow and Neural Representability of One-Dimensional Rotated Cluster States arXiv · Oct 29, 2026This paper studies how measurement outcomes in one-dimensional rotated cluster states stay conditionally dependent over long distances, despite an exact matrix product state bond dimension of 2. It compares the conditional mutual information of an entanglement-swapping endpoint readout with a bulk readout of the locally equivalent conventional cluster state, using the spin-1 AKLT chain as an exact control. The paper also benchmarks several neural learners on the same target, finding that building the small virtual memory into the architecture greatly eases optimization.

Closed-form solutions for fully quantized parametric amplification

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Analytic Solutions To Fully Quantized Parametric Amplification arXiv · Oct 29, 2026This paper derives analytic expressions for how observables evolve under the fully quantized trilinear Hamiltonian that describes quantum three-wave mixing and parametric amplification. Starting from a coherent pump and vacuum signal and idler, the authors reorganize the Heisenberg expansion into resummed depletion and return profiles, giving directly evaluable expressions for correlations up to third order. Numerical benchmarks reported in the paper show errors around 10^-12 across the full pump depletion and below 10^-3 over dozens of depletion-and-back-conversion cycles.

Efficient experimental classification of quantum data using quantum kernels

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Provably efficient experimental classification of quantum data with quantum kernels arXiv · Oct 29, 2026The paper proposes a framework for efficient quantum-state classification that reduces the number of measurements needed, deriving conditions under which the measurement count grows polynomially with system size. It applies this to classifying stellar rank, a measure of non-Gaussianity, in continuous-variable quantum computing. The authors experimentally classify single-mode states with stellar rank zero and one on a programmable photonic processor, reporting accurate results despite experimental imperfections.

A family of fermionic relative Rényi negativities in Sachdev-Ye-Kitaev models

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A Zoo of Fermionic Relative Rényi Negativities in the Sachdev-Ye-Kitaev Models arXiv · Oct 29, 2026This paper introduces relative Rényi negativities as entanglement witnesses for mixed fermionic states. The authors relate fermionic partial time reversal to the size superoperator to obtain a path-integral representation. They evaluate these quantities in thermal states of the SYK model and the Maldacena-Qi coupled SYK model using a large-N expansion. The study identifies a class that plausibly approximates logarithmic negativity and finds first-order entanglement transitions not visible in simple observables.

NAKO: A Benchmark for Testing and Diagnosing Compilers for Neutral-Atom Quantum Computers

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NAKO: A Benchmarking Framework for Evaluating and Diagnosing Neutral-Atom Quantum Compilers arXiv · Oct 29, 2026Neutral-atom quantum processors must jointly schedule gates, place atoms, and move them in parallel, so compiler choices drive physical costs. This paper introduces NAKO, a benchmarking framework that pairs each benchmark with an executable reference schedule to measure resource gaps in compiler outputs. Controlled interventions on reference mappings and intermediate states trace excess costs to specific compiler decisions. In a 648-run evaluation of Enola and OLSQ-DPQA, NAKO identifies distinct bottlenecks in each compiler and validates resource savings from targeted fixes.

Quantum field theory with scale-dependent weighted measures in momentum space

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Quantum field theory with scale-dependent weighted measures: nonlinear momentum representations, vacuum fluctuations, and causal structure arXiv · Oct 29, 2026The paper revisits constructing free quantum fields using weighted measures in momentum space, adding an independent energy scale that recovers the conventional theory at low momenta. The resulting family is described by a dimensionless spectral function, with the spatial weight linked to the Euclidean Snyder algebra as one special case. It also examines connections to modified dispersion relations and nonlinear momentum coordinates, and analyzes equal-time algebra, vacuum fluctuations, two-point functions and nonlocal causal structure for the complex Klein-Gordon field.

Dissipation dilution boosts SiV coupling to diamond nanomechanical beams

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Dissipation dilution enhances SiV coupling to vdW diamond nanomechanics arXiv · Oct 29, 2026This paper experimentally studies a tensioned diamond nanobeam platform where strain couples negatively charged silicon vacancy centers to a mechanical resonator. By monitoring the SiVs' optical response, the authors observe that dynamical strain localizes near the clamps under static strain. This enhances both SiV-mechanical coupling and mechanical coherence, and yields a strain sensitivity with much better accuracy than prior literature values.

Quantum Optimization Using Cavity Dissipation to Escape Local Minima

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Efficient Quantum Optimization via Dissipative False Vacuum Decay arXiv · Oct 29, 2026This paper proposes a cavity-based dissipative quantum solver for a class of NP-hard combinatorial optimization problems encoded as atomic-spin Hamiltonians. The method uses dissipative false-vacuum decay in configuration space to escape metastable local minima in rugged energy landscapes. Numerical studies on MaxCut and Maximum Independent Set identify favorable parameter regions, and time complexity estimates based on finite-size scaling are reported as more favorable than standard Grover search.

A design and verification flow for quantum circuits modeled on VLSI practice, tested on pi estimation

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A VLSI-Like Design and Verification Flow for Quantum Circuits: A Case Study in PI Estimation arXiv · Oct 29, 2026This paper proposes a four-level design and verification flow for quantum circuits, adapted from conventional VLSI digital design, covering behavioral modeling, register-transfer level, gate level, and integration with quantum algorithms. It uses quantum Monte Carlo pi estimation as a case study to show a path from specifications to large-scale circuit implementation. Classical simulations indicate that replacing random sampling with grid sampling yields a quadratic improvement in this case without any quantum computation, suggesting the speedup may come from the sampling strategy rather than the quantum amplitude estimation circuit.

Beyond Direct Imaging: Quantum Measurement Design for Small-Target Detection in UAV Hyperspectral Sensing

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Beyond Direct Imaging: Quantum Measurement Design for Small-Target Detection in UAV Hyperspectral Sensing arXiv · Oct 29, 2026The paper proposes a quantum-assisted framework for detecting small targets in UAV hyperspectral sensing by comparing direct imaging with spatial-mode measurements. Simulations based on measured mineral spectra and published UAV acquisition scales, at a shared active-exposure budget, show it outperforms complete direct imaging. At an empirical 1% region-level false alarm rate, detection for a representative target rises from 62.95% to 69.65%.

Spatial-mode selection for measuring mineral absorption in small regions

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Spatial-Mode Selection for Local Mineral Absorption Spectroscopy arXiv · Oct 29, 2026This paper proposes a quantum-inspired measurement framework that uses spatial-mode demultiplexing (SPADE) to keep the absorption response of a small mineral region while reducing background light before detection. In equal-time simulations that include localization uncertainty, alignment time, calibration, and detector costs, it reduces absorption-depth root-mean-square error by 14% to 26% across five absorption strengths compared with all-pixel direct imaging using the same background freedom.

Force sensing in a recoverable bosonic quantum memory, a paper on sensing an external force while protecting quantum information

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Force Sensing in a Recoverable Bosonic Quantum Memory arXiv · Oct 29, 2026The paper constructs finite-energy bosonic codes that let a single oscillator sense an external force while actively protecting an unknown logical qubit. Logical amplitudes are encoded across discrete wave-packet sites, and the force signal is captured in a shared internal coordinate, enabling a probe readout independent of the logical state under continuous photon loss. Binomial site recovery is shown to suppress memory infidelity and memory-probe correlations at stated orders, and superconducting circuit benchmarks identify preferred encoding regimes for hardware.

Competition Between Resonance and Transition Channels in Cavity-Assisted Floquet-State Stabilization

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Resonance and Transition-Channel Competition in Cavity-Assisted Floquet-State Stabilization arXiv · Oct 29, 2026This paper studies coupling a driven quantum system to a dissipative cavity to autonomously stabilize Floquet eigenstates. At intermediate driving frequencies, meeting the resonance condition alone is shown to be insufficient, because the steady state depends on the interplay between resonance selection and cavity-induced transition strengths. This interplay can yield successful stabilization, mixed steady states despite resonance, or complete breakdown near Floquet-zone hybridization. The authors state that the same mechanism extends to multilevel spin-S systems.

Narrowband and ultrashort-pulse-like probing in CARS using twin beams and SFG readout

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Signatures of Narrowband and Ultrashort-Pulse-Like Probing in Coherent Anti-Stokes Raman Scattering Using Twin Beams and Sum-Frequency Generation Readout arXiv · Oct 29, 2026This paper theoretically studies coherent anti-Stokes Raman scattering (CARS) driven by bright twin beams, with sum-frequency generation (SFG) as the readout. Expressing the SFG output through quantum-field correlation functions reveals several correlation structures tied to different interaction pathways on the bra and ket sides. Frequency correlations between the CARS probe and SFG gating fields let the two fields act together as an effective narrowband probe, avoiding probe-induced spectral convolution.

Beyond energy bounds: comparing Schrödinger eigenstates

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Beyond energy bounds: comparing Schrödinger eigenstates arXiv · Oct 29, 2026The paper derives comparisons between eigenstates of ordered Schrödinger operators, extending energy bounds to ground-state overlaps, spatial distributions and nodes. In one dimension and radially, a single crossing condition on the potential difference orders ground-state likelihood ratios and monotone observables. For Yukawa ground states, Hulthén comparison functions bound overlaps, radial moments and the density at the nucleus, yielding a lower bound of about 1.13611 on the scaled critical screening parameter.

Reverse quantum annealing to compute molecular ground-state energies

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Reverse Quantum Annealing for Ground-State Energy Calculation in Molecule arXiv · Oct 29, 2026This paper reports reverse quantum annealing calculations of ground-state energies for alkaline-earth monofluoride molecules. The Dirac-Coulomb electronic Hamiltonian is split into sub-QUBOs, and forward-annealing solutions are refined with optimized reverse-annealing schedules to systematically reduce residual configuration errors. Electronic ground-state wave functions and energies are obtained with the Quantum Annealing Eigensolver algorithm, and the authors present this as a route toward sub-milliHartree chemical accuracy.

A rhombic spin-1 model explaining a room-temperature GaN emitter's magnetic resonance lines

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A rhombic spin-1 interpretation of a room-temperature GaN emitter arXiv · Oct 29, 2026This paper studies optically detected magnetic resonance from single defects in GaN at room temperature. It argues that a minimal S=3/2 model cannot explain a g≈4 line in a common defect class, and proposes a rhombic S=1 model that reproduces three line positions with rms errors of 8.1-9.8 MHz. The authors state that existing data cannot uniquely establish the S=1 assignment and propose a zero-field sweep to test it directly.

The Fate of Quantum Magic: How a Non-Entanglement Quantum Resource Dies or Persists Under Thermal and Dynamical Evolution

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Fate of Quantum Magic arXiv · Oct 29, 2026This paper studies quantum magic, a quantum resource distinct from entanglement that measures how far a state departs from states stabilized by products of Pauli operators. The authors develop a framework to evaluate magic in generic many-body states and examine how it changes under thermal and dynamical evolution. They report a thermal sudden death of magic in the transverse field Ising model, generic spin chains, and the Kitaev spin liquid, and discuss how magic equilibrates after quantum quenches. The paper also introduces non-local magic and proposes a way to witness volume-law frame-robust magic in quantum materials using neutron scattering.

High-bandwidth magnetic sensing with bulk diamond NV centers

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High bandwidth heterodyne sensing with bulk NV diamond arXiv · Oct 29, 2026The paper presents a magnetic quantum sensor that uses heterodyne mixing under strong optical and microwave driving, reaching MHz-scale instantaneous bandwidth with 548 pT/√Hz sensitivity in bulk nitrogen-vacancy diamond. The authors then extend the bandwidth of a single resonance to 48 MHz using a strong magnetic gradient and many individually modulated microwave control fields. The peak sensitivity in this configuration is 8.5 nT/√Hz.

Fully quantum diffusion model generating synthetic malware records, with limited utility and costly sampling

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Fully Quantum Latent Diffusion for Synthetic Malware Records: Effective Denoising, Limited Class Information, and Costly Post-Selection arXiv · Oct 29, 2026This paper introduces a fully quantum latent diffusion model that generates synthetic malware opcode-sequence records, using a parameterized circuit with one mid-circuit measurement and no classical neural layers. Across 17 malware families, the circuit cut denoising infidelity by 63%, yet classifiers trained on its records scored a macro-F1 of 0.11 on real records, below 0.44 for a classical diffusion model. The authors conclude that quantum generators of shareable security data need joint evaluation of utility, privacy, and sampling cost.

Reducing Errors in Quantum Eigensolver Molecular Calculations Using Extended Random Phase Approximation

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Mitigating Errors in Variational Quantum Eigensolver Calculations through Extended Random Phase Approximation arXiv · Oct 29, 2026This paper proposes an error-mitigation method based on the extended random phase approximation (ERPA) to reduce hardware noise in variational quantum eigensolver (VQE) molecular simulations. It reconstructs the two-particle reduced density matrix from approximate transition density matrices, with a DMRG calculation supplying a noise-free one-particle density matrix. Benchmarks on IBM quantum hardware for water double-bond stretching and cyclobutadiene automerization show energy errors reduced by orders of magnitude, and adding multireference adiabatic connection corrections recovers dynamical correlation.

Execution bias and repeatability in molecular VQE energy evaluation on quantum hardware

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Execution bias, repeatability and mitigation cost in parameter-frozen molecular VQE energy evaluation arXiv · Oct 29, 2026This paper tests molecular energy estimates from variational quantum eigensolver states on two 156-qubit IBM Heron processors, Aachen and Pittsburgh, with parameters and circuits frozen. It compares raw measurements against zero-noise extrapolation and readout error mitigation in terms of residual error, cost, and repeatability. The authors find that a smaller statistical error bar does not guarantee a more accurate energy. They recommend workload checks and repeated measurements before taking additional samples.

Tunable Floquet exchange spectroscopy using Hong–Ou–Mandel interference

2026-10-29T00:00:00+09:00

Drive-tunable Floquet exchange spectroscopy with Hong--Ou--Mandel interference arXiv · Oct 29, 2026This theoretical study shows that delay-resolved Hong–Ou–Mandel (HOM) coincidence measurements can probe how Floquet driving changes two-photon exchange in a collectively coupled cavity. A frequency-entangled signal photon scatters from the driven cavity while its idler serves as a delayed reference, and averaging over an unsynchronized drive phase preserves exchange interference within each output order. Fourier transforming the coincidence trace reveals two drive-dependent exchange branches tied to the Floquet-polariton spectrum.

The geometry of Floquet states: a study of the moduli space of periodic Hamiltonians

2026-10-29T00:00:00+09:00

The geometry of Floquet states arXiv · Oct 29, 2026This paper studies the moduli space of periodic Hamiltonians with nondegenerate Floquet spectrum, called "good" Hamiltonians. The corresponding Floquet states give a geometric model of this space, expressed using configuration spaces, flag manifolds, and principal bundles. A corollary of the main result is the complete determination of the rational cohomology ring of the space of good periodic Hamiltonians. The paper also considers adiabatic driving of a one-parameter family of such Hamiltonians and proposes two conjectures describing the resulting asymptotic quantum evolution, as Floquet analogues of the adiabatic theorem.

Using neural networks to infer how many times a quantum channel has been used

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Inferring the Number of Quantum State Transfers with Neural Networks arXiv · Oct 29, 2026This paper studies repeated-use quantum state transfer, where memory builds up in the channel between uses because it is not reset. The authors train a simple feed-forward neural network that takes only the Bloch vectors sent and received in a single use of an XX spin-chain channel and identifies the use number with over 90% accuracy. Using the channel's U(1) symmetry to form a reduced two-component representation raises accuracy to about 95%.

Gravity-mediated entanglement in interferometers with repeated splitting

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Gravitationally Mediated Entanglement in Interferometers with Repeated Splitting arXiv · Oct 29, 2026This paper proposes and analyses protocols with repeated splitting stages, each doubling the occupied paths, to generate entanglement between spatially separated masses mediated by gravity. The authors derive an exact lower bound on the change in negativity and an explicit condition for when an additional splitting stage improves readout. Numerical simulations show an advantage in positional negativity over the parameter ranges considered.

Gravity Between Nuclear Clocks: Using Quantum Nuclear Energy Superpositions to Probe Short-Range Gravity

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Gravitational Interactions in Nuclear Clocks arXiv · Oct 29, 2026This paper studies whether the mutual gravitational interaction among a large ensemble of nuclear clock nuclei could be observed. The authors analyze the gravitational redshift caused by neighboring nuclei and treat nuclear energy superpositions as gravitational sources, producing a quantum gravitational interaction between pairs of nuclei. They find that for a macroscopic number of nuclei, such as in a solid-state thorium clock, the resulting frequency shift may become non-negligible.

Memory Effects Limiting Repeated Entanglement Distribution

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Memory-Induced Limits on Entanglement Distribution arXiv · Oct 29, 2026This paper studies the practical limits of distributing entanglement through quantum channels reused without reinitialization. It shows that excitations left in the channel by earlier uses act as a memory source that progressively suppresses coherent quantum transmission. The authors derive an analytical lower bound on quantum capacity and combine it with a Holevo-Werner semidefinite-programming upper bound to define a capacity window.

Key Performance Evaluation of Relativistic Quantum Key Distribution Through Turbulent Free-Space Optical Channels

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Key Evaluation of a Relativistic Quantum Key Distribution Over a Turbulent Free-space Optical Channel arXiv · Oct 29, 2026This paper examines how atmospheric turbulence affects relativistic quantum key distribution (RQKD) over free-space optical links, for both single-photon and coherent-state versions. The authors build a model that adds turbulence-induced phase fluctuations to the key-rate analysis and run numerical simulations under realistic channel conditions. Turbulence lowers interference visibility and degrades performance, with the severity depending on the ratio of interferometer separation or time separation to Fried's parameter.

Engineering Baths to Generate Multipartite Entanglement

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Generating Multipartite Entanglement via Structured-Bath Engineering arXiv · Oct 29, 2026This paper proposes a dissipative method for preparing genuinely multipartite-entangled steady states using independent local reservoirs, an Abelian strong symmetry, and temporal bath correlations. In interacting Ising chains, flat baths are shown to erase Ising-axis correlations exponentially, while structured baths convert temporal correlations into classical spatial ones that strong symmetry lifts into quantum entanglement. Engineering the bath spectrum lengthens the correlation length, enabling GHZ-like states to be prepared from separable initial states.

A benchmark family of Ising models that can be solved exactly.

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Generalized Mean-Field Ising Model as a Benchmark Family with Exact Solutions arXiv · Oct 29, 2026The paper introduces the Generalized Mean-Field Ising (GMFI) family, a class of densely connected, inhomogeneous Ising Hamiltonians whose ground states can be obtained exactly. The exact solution reveals hidden low-dimensional structure and allows a number-theoretic classification of system sizes and degenerate ground states. The family is used to benchmark quantum and classical optimization methods, including quantum annealing, D-Wave experiments, QAOA, and several classical algorithms. The authors report unexpected system-size-dependent oscillations in the quantum-annealing gap.

Eigenvector-Continued Green's Function Method: A Fast Reduced-Order Approximation of Many-Body Green's Functions

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An Eigenvector-Continued Green's Function Method arXiv · Oct 29, 2026The paper notes that emulating the Green's function with reduced-order equations is difficult because it contains a large amount of information, including one-particle spectra, the one-body density matrix, and the ground-state energy. The authors introduce a systematically improvable emulator based on eigenvector continuation and moment-matching. The resulting approximation is obtained by solving linear equations, which separates the computation into offline and online stages.

Mixed-state topological transition in a non-Abelian Kitaev spin liquid with emergent supersymmetry

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Mixed-State Topological Transition and Emergent Fractionalized Supersymmetry in the Non-Abelian Kitaev Spin Liquid arXiv · Oct 29, 2026This paper studies a topological transition in a mixed quantum state of the non-Abelian Kitaev spin liquid, driven by bond dephasing noise. The noise maps onto interacting fractionalized Majorana systems, allowing sign-problem-free Monte Carlo simulations. At an interface between topological and trivial Kitaev states, a gapless Majorana mode appears, and at the dephasing-driven transition this mode gains emergent N=1 supersymmetry. Simulation results agree with the exact supersymmetric values.

A Primer on Instanton Physics: A Short Course

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A Primer on Instanton Physics - A Short Course arXiv · Oct 29, 2026These six lectures were given at the University of New Brunswick from 6 to 21 October 2026 for senior undergraduates and beginning graduate students. They introduce instantons in quantum mechanics and quantum field theory. The first four lectures cover particle mechanics as background, and the last two cover applications in semi-classical field theory.

Computing quenched thermodynamics of disordered spin models with a quantum circuit that uses an ancilla and imaginary-time evolution

2026-10-29T00:00:00+09:00

Quenched Thermodynamics from Ancilla-Assisted Imaginary-Time Evolution arXiv · Oct 29, 2026This paper presents a quantum algorithm for computing quenched disorder averages in the transverse-field Ising model, with coupling configurations grouped into gauge classes. Approximate Gibbs states are prepared through ancilla-assisted imaginary-time evolution, and the ancilla measurement record indicates which gauge class each energy estimate belongs to. On a 3×3 open lattice, a one-step circuit resolves all sixteen flux classes, and thermodynamic integration yields a quenched free-energy estimate.

Measuring the edge heat-transport constant of a Kitaev spin liquid from spectra

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Gravitational anomaly spectroscopy of a Kitaev spin liquid arXiv · Oct 29, 2026This paper proposes measuring the chiral central charge c of a two-dimensional topological phase from the spectrum of edge response to weak modulations of edge couplings, rather than through thermal transport. Using the Virasoro algebra, the authors derive absorption weights that depend on c and the mean edge energy, and build a combination equal to c. Numerical results for the Kitaev honeycomb spin liquid are reported, along with robustness tests under coupling errors, interacting edges, and a quantum-processor protocol.

Quantum algorithm for molecular geometries and reaction pathways on a quantum processor

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Sample-Based Quantum Diagonalization for Variable Molecular Geometries arXiv · Oct 29, 2026This paper introduces VGSQD, a variable-geometry extension of sample-based quantum diagonalization that reuses quantum samples from a reference geometry for displaced geometries, reducing quantum cost. Using circuits of up to 124 qubits on the IBM Heron r2 processor ibm-quebec, the authors determine the equilibrium geometry and energy of the beryllium dimer and water. They also compute the minimum energy path and energy barrier of a hydrogen exchange reaction, with results comparable to CCSD(T) and DMRG.

Quantum observables of nonperturbative superradiant scattering, a theory of how many coherent spins scatter particles collectively.

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Quantum Observables of Nonperturbative Superradiant Scattering arXiv · Oct 29, 2026The paper studies inelastic scattering from N coherent spins or any two-state system, showing the scattering scales as N², so the Born approximation fails at large N even when coupling is weak. The authors develop a nonperturbative theory of this superradiant scattering and its backreaction on the spins. The theory is said to apply to searches for millicharged particles and to neutron and charged-particle beams that could test quantum protocols for detecting cosmic relics.

Goldbach representations in quantum optics and metrology: linking prime-number splittings to photon statistics and precision limits

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Goldbach Representations in Quantum Optics and Metrology arXiv · Oct 29, 2026The paper links Goldbach representations to photon-number statistics in a quantum-optical setup. An even-number Fock state is sent into a stochastic beam splitter with uniformly distributed transmissivity, and the two outputs are projected onto prime subspaces. Each successful outcome corresponds to a Goldbach representation, and the averaged detection probability is proportional to their number. Using the Hardy–Littlewood asymptotic formula, the authors show that fixed transmissivity yields standard quantum limit scaling, while an equal superposition of representations yields Heisenberg scaling in phase estimation.

Comparing homodyne and heterodyne detection for classifying optical quantum state families from finite detection records

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Homodyne versus heterodyne detection for classifying families of optical quantum states from finite records of detection events arXiv · Oct 29, 2026The paper compares heterodyne detection with homodyne detection (using filtered back-projection to reconstruct the Wigner function) for identifying one of seven optical quantum state families, including GKP states, from finite detection records. With convolutional networks at N=100 events and 20% dephasing in the first family set, heterodyne detection outperformed homodyne by 14.1 percentage points, a difference that remains significant after multiple-comparison adjustment. At N=10^3 and 10^4 no significant difference was found, and the results concern a reconstruction-based pipeline rather than homodyne detection in general.

Using cold atoms in optical tweezers to search for micron-scale fifth forces

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Probing micron-range fifth forces with cold atoms in optical tweezer arrays arXiv · Oct 29, 2026This paper proposes a new method for searching for fifth forces at micron scales by resonantly exciting the motion of ground-state-cooled atoms held in optical tweezer arrays. The authors develop a homodyne readout protocol based on sideband thermometry that can approach the Standard Quantum Limit. According to the paper, this raises the discovery reach for fifth forces by up to four orders of magnitude over existing constraints, and can also probe extra-dimension models beyond the current tabletop state of the art through the parametric enhancement of higher-dimensional gravity.

Quantum privacy amplification using hyperentanglement for quantum and classical signals sharing fiber networks

2026-10-28T00:00:00+09:00

Hyperentanglement-enabled Quantum Privacy Amplification for Classical-Quantum Coexistence in Fiber Networks arXiv · Oct 28, 2026This paper addresses how Raman scattering noise from high-power classical traffic degrades quantum signals in shared fiber networks. It implements single-copy entanglement distillation using energy-time and frequency hyperentanglement to perform quantum privacy amplification at the physical layer. The method discards uncorrelated Raman photons by exploiting frequency anti-correlations of down-conversion. In a 20 km fiber testbed, the tolerance to classical launch power improved by 4 dB, extending the secure key threshold from -13.3 dBm to -9.3 dBm.

Experimental methods for building quantum gates on superconducting NISQ hardware

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Quantum Gate Engineering in Superconducting NISQ Platforms: Experimental Methods and Emerging Directions arXiv · Oct 28, 2026This review guides researchers and engineers through implementing quantum gates on superconducting NISQ devices. It compares conventional transmons with alternative superconducting qubit and processor designs. It describes how single- and two-qubit operations are built with microwave and flux pulses, including calibration workflows, and how truth tables and quantum process tomography are used for benchmarking.

Competition and cancellation in a tilted Rice–Mele chain: exact Wannier–Stark offset

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Competition and cancellation in a tilted Rice--Mele chain: exact Wannier--Stark offset and spectral readout arXiv · Oct 28, 2026This paper studies the staggered offset A in the Wannier–Stark ladder of a tilted Rice–Mele chain, which arises from competition between staggered onsite energy and dimerized hopping. The authors determine A using a strong-field series and a two-band Floquet expression, and show that cancellation restores equidistant spectral levels. They also describe how the offset can be read from the static spectrum on odd-length chains and how cancellation appears as two sidebands merging into one line.

Pulse-Informed Placement of Parallel Two-Qubit Gates in Qubit Arrays

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Pulse-Informed Physical Placement for Parallel Two-Qubit Gates in Qubit Arrays arXiv · Oct 28, 2026This paper studies how to choose physical couplers and design simultaneous control pulses for parallel controlled-Z gates in heterogeneous frequency-tunable transmon arrays. The authors combine a structural quantum multi-domain matrix (QMDM) with quantum optimal control, ranking and promoting candidate placements based on the pulses optimized for each one. On 30 held-out synthetic 3×3 processors, the median final projected fidelity was 0.993826 for pulse-informed placement versus 0.984981 for calibration-based placement, using 59.1% fewer optimizer iterations than an exhaustive reference. The validation covers two simultaneous gates.

Learning Grover mixers for constrained optimization: a study of training a quantum circuit to prepare feasible-state superpositions for improved constrained optimization.

2026-10-28T00:00:00+09:00

Learning Grover mixers for constrained optimization arXiv · Oct 28, 2026The paper proposes a two-stage variational method that first trains a parameterized quantum circuit, using an entropy-based cost function, to prepare a uniform superposition over feasible states. This circuit is then embedded in GM-QAOA as the initial state and, with its inverse, forms a Grover mixer. Tested on the Maximum Weight Independent Set and Multidimensional Knapsack problems, it consistently improves over standard QAOA for MWIS but gives only marginal gains for MKP, with advantages shrinking as problem size grows. The authors attribute this to harder mixer training and note a trade-off between performance gains and the extra training resources required.

Collaborating AI agents that run autonomous quantum spin experiments

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Collaborative AI agents for autonomous experimental research with solid-state quantum spins arXiv · Oct 30, 2026This paper presents an autonomous research laboratory in which large language model agents review each other's work and can stop or redirect investigations. The agents study ensembles of quantum spins in diamond, deriving the minimum number of calibration settings needed to predict responses to a family of microwave pulse sequences. An initial experiment matched the predictions, but repeated reference measurements revealed signal drift, so the agents revised the protocol without relaxing their acceptance criteria. The revised experiment met those criteria and supported the theoretical predictions.

Quantum communication via a state discrimination method

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Quantum communication: a discrimination approach arXiv · Oct 30, 2026This paper proposes a state discrimination approach to unassisted quantum communication over a noisy quantum channel. Building on the operational duality between entanglement recovery and state discrimination, the authors construct entanglement-generation codes with explicit decoders based on Petz recovery maps. The error bounds hold for any number of channel uses and are expressed in terms of Petz-Rényi coherent information. For product sources, the error decays exponentially at rates below the coherent information.

Quantum query cost of finding tournament winners

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Quantum Query Complexity of Tournament Solutions arXiv · Oct 29, 2026This paper studies how many quantum queries are needed to compute tournament solutions, which pick winners from the results of all pairwise comparisons among N alternatives. Classically these problems need Θ(N²) queries. The authors show the top cycle can be computed with Θ̃(N) quantum queries and a Condorcet winner found with Θ̃(√N), while finding a strong king needs Θ(N^{3/2}) queries.

Automated Verification of Hamiltonian Simulation Using Quantum Signal Processing

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Automated Verification of Hamiltonian Simulation by Quantum Signal Processing arXiv · Oct 29, 2026This paper presents what the authors believe is the first fully automated verification framework for Hamiltonian simulation based on quantum signal processing (QSP). The framework exploits the algorithm's structure, proving that the all-zero ancilla block is proportional to the target Hamiltonian and inferring the subnormalization factor automatically. It then verifies the QSP layer by extracting the implemented polynomial and certifying its approximation error. The implementation handles block encodings of Pauli-sum Hamiltonians with up to 256 system qubits.

SeQUeNCe.DQC: A Full-Stack Simulator for Distributed Quantum Computing

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SeQUeNCe.DQC: Full-stack Simulation of Distributed Quantum Computing arXiv · Oct 29, 2026This paper presents SeQUeNCe.DQC, a new top-level module in the SeQUeNCe package that compiles quantum circuits into network-aware execution plans and runs them using existing quantum-network modules. The authors validate it by reproducing a two-node trapped-ion Grover experiment and comparing success probabilities with a reported 71% benchmark. They also study how compiler strategy, topology, and memory capacity affect execution time and success rate, finding that hybrid compilers mixing TeleGate and TeleData outperform pure gate-teleportation strategies.

QSoftCore: A Conceptual Model for Quantum Software Engineering

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QSoftCore: A Conceptual Foundation for Quantum Software Engineering arXiv · Oct 29, 2026This paper presents QSoftCore, a conceptual model that reorganizes established quantum computing concepts from a software engineering perspective. It links quantum applications, computational problems, algorithms, configurations, programs, and paradigm-specific computation specifications with state evolution, execution results, and backends. The authors report that the model provides shared referents for computations, executions, deployment configurations, backends, and measurement evidence across the quantum software engineering lifecycle.

Quantum relay optical link using squeezed signals and energy harvesting

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Time-Switching Energy-Harvesting Quantum Relay-Assisted FSO Communication with Displaced Squeezed Signaling arXiv · Oct 29, 2026This paper studies a quantum relay-assisted free-space optical link in which a decode-and-forward relay is powered by time-switching optical energy harvesting and forwards data using displaced squeezed signaling. Turbulence-induced loss is modeled as a pure-loss bosonic channel with a truncated Gamma-Gamma transmissivity distribution. The authors derive error and fidelity expressions for coherent and squeezed hops and analyze when squeezing improves throughput.

Robust optimization of repulsive Casimir forces in a biased-semiconductor cavity

2026-10-02T00:00:00+09:00

Passive-reflector bounds and robust bilateral nonequilibrium Casimir repulsion arXiv · Oct 2, 2026This paper studies how to achieve nonequilibrium Casimir–Lifshitz repulsion in a planar stack of conductors, vacuum, and biased GaAs, framing the design as a robust constrained optimization under fabrication and drive uncertainty. In the optically thick-slab limit, the authors prove that a symmetric optimizer exists. At 300 K with gap uncertainty of ±10 nm and drive uncertainty of ±0.005, the optimized design gives a worst-case outward pressure of 2.257 mPa, and a finite-slab scattering calculation agrees closely with the reduced model.

A quantum battery charged selectively by frequency through an anharmonic mediator

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Spectral and Impedance Matching for Multi-excitation Charging of an Interacting Quantum Battery via an Anharmonic Mediator arXiv · Sep 30, 2026The paper studies a finite-time charging scheme in which a driven two-level system transfers nonequilibrium resources to an interacting two-qubit battery via a weakly anharmonic three-level mediator. The mediator's lower transition enables nearly complete single-excitation transfer, while a two-excitation cascade charges the doubly excited battery state with a modest efficiency reduction. Detuning scans quantify spectral tolerance, and the full charge-discharge cycle's energy balance closes to numerical precision.

Limits on preparing light states via phase-space majorization

2026-10-28T00:00:00+09:00

Fundamental limits on photonic state preparation from phase-space majorization arXiv · Oct 28, 2026This paper studies probabilistic conversions between quantum states of light, deriving fundamental bounds for both exact and approximate transformations. The authors develop a theory of weak, fully relative majorization that compares the disorder of phase-space functions. Focusing on Wigner functions in multimode photonic systems, they establish no-go results and tradeoff relations for conversions involving squeezed, cat, Gottesman-Kitaev-Preskill, and Fock states. The work derives novel bounds and recovers known tight ones. ★★★★ Notable: The authors introduce a phase-space relative majorization theory yielding new no-go bounds and tradeoffs for photonic state preparation, recovering known tight bounds.

Toffoli gates with no spare qubits, and T-gate counts for Boolean oracles

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Ancilla-free randomized Toffoli gates and the T-count of Boolean oracles arXiv · Oct 28, 2026This paper studies the T-gate cost of Boolean oracles in fault-tolerant Clifford+T circuits. The authors compute sampled parities in place on the gate's own controls, which removes the need for extra qubits once the gate is large enough, using about 8 T gates per bit of precision per random circuit. The same holds for exclusive-ors of affine subspace indicators. The paper also shows that a random set of fixed density needs exponentially many T gates at constant error, whereas an affine subspace of the same density needs a constant number. ★★★★ Notable: The authors remove extra ancilla qubits from the Gosset et al. randomized Toffoli construction, using about 8 T gates per bit of precision, and compare against lower bounds.

Coherent errors, syndrome extraction, and magic robustness in stabiliser codes

2026-10-28T00:00:00+09:00

Coherent errors, syndrome extraction and the Robustness of Magic in stabiliser codes arXiv · Oct 28, 2026This paper studies how coherent errors change the magic of states encoded in stabiliser codes, measured by the Robustness of Magic. The authors show that a unitary error adds one copy of the error's Choi state to the encoded magic, and that syndrome extraction removes this copy, restoring the logical robustness. They also give magic lifetimes for stored single-qubit magic states under Pauli noise, reporting that choosing the plane of the stored state extends these lifetimes about 1.5x on rotated surface codes under low code-capacity depolarising noise.

Using memory effects to boost quantum-battery capacity

2026-10-28T00:00:00+09:00

Harnessing Non-Markovian Memory for Quantum-Battery Capacity arXiv · Oct 28, 2026This paper studies whether the memory in non-Markovian dynamics can be actively used to increase quantum-battery capacity, taking a thermodynamic view. Within the process-tensor framework, it compares memoryless and memory-enhanced strategies and defines their gap as a memory-assisted capacity advantage. The authors prove this advantage vanishes for Markovian process tensors and is bounded by a trace-distance measure of non-Markovianity. A continuous-time example with random telegraph dephasing shows that memory built up during evolution can improve capacity retention.

Tan's contact in trapped spin-orbit-coupled Fermi gases at finite temperature, a measure linking many-body and two-body quantum behavior.

2026-10-28T00:00:00+09:00

Tan's Contact for Trapped Spin-Orbit-Coupled Fermi Gases at Finite Temperature arXiv · Oct 28, 2026This paper uses path integral Monte Carlo simulations to study Tan's contact in spin-orbit-coupled Fermi gases at finite temperature. Previous work covered only zero temperature. The authors find that thermal effects change how the contact scales with spin-orbit coupling strength, weakening the linear relation seen at zero temperature and producing a non-monotonic dependence.

Coherent electron lensing in superconducting graphene junctions

2026-10-28T00:00:00+09:00

Coherent Electronic Lensing in Proximitized Graphene arXiv · Oct 28, 2026This paper uses scanning gate microscopy (SGM) to study Fabry-Pérot interference in a ballistic graphene Josephson junction. Spatial maps reveal circular interference fringes caused by two effects of the tip potential: a global shift of the Fermi wave vector and a local perturbation that adds oscillations. An analytical model attributes the local response to coherent electron lensing, where the tip changes the phase along interfering paths. The authors show this affects superconducting transport and establish SGM as a tunable local lens for controlling interference in such devices.

Input allocation for quantum systems based on controllability

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Controllability-Based Input Allocation in Quantum System arXiv · Oct 28, 2026This paper studies how local perturbations propagate through quantum dynamics governed by the Schrödinger equation. It introduces a volumetric controllability allocation score (V-CAS), computed from a multiobservable quantum-control Gramian via simplex-constrained log-determinant optimization over virtual local Hamiltonian perturbations. The authors give a matrix-product-state implementation with an error bound, and numerical experiments show the score identifies finite-time influence patterns different from correlation- and entanglement-based measures.

Geometry of Magic Robustness and Directed State Conversion

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Robustness of Magic and the Directed Geometry of State Conversion arXiv · Oct 28, 2026This paper introduces a state-space distance calibrated by stabilizer states, based on the dual structure of the robustness of magic (RoM), and shows that RoM equals the distance to the set of free states. It extends this geometry to state conversion by defining a directed conversion deficiency, the distance from a target state to the states freely reachable from a given input. For single-qubit systems, the authors analytically construct a continuous family of mixed states with identical RoM but asymmetric convertibility.

Revisiting the fermionic Unruh effect: entanglement and correlation under symmetric transformations

2026-10-28T00:00:00+09:00

Fermionic Unruh effect revisited: Entanglement and correlation dynamics under symmetric transformations arXiv · Oct 28, 2026This paper examines how the vacuum seen by a uniformly accelerated observer affects quantum correlations shared with an inertial partner. The authors introduce a symmetric Unruh-like map that yields, for a Bell state, a bit-flip channel whose flip probability is the Fermi-Dirac occupation at the Unruh temperature. Using negativity, mutual information, and all six pairwise quantum discords, they find that entanglement and discord between the inertial observer and the accessible mode both vanish at infinite acceleration, leaving one bit of classical correlation.

How Spectral Reduction Selects the Observable Imprint of Dirac Quantum Geometry

2026-10-28T00:00:00+09:00

Spectral Reduction Selects the Observable Imprint of Dirac Quantum Geometry arXiv · Oct 28, 2026This paper examines how fixing the energy in relativistic electron vortices changes the observable signature of quantum geometry. The authors derive a Hermitian selection rule for first-order observables in momentum-dependent internal subspaces and show that the magnetic correction for the free positive-energy Dirac doublet is an exact non-Abelian Berry-curvature contraction. Changing the relative phase between the two spinor components switches this correction from zero in a conserved transverse-helicity sector to a finite value in a radial coherent superposition.

Quantum change point metrology: extra Bayes risk of locating a change point and estimating its amplitude in one measurement

2026-10-28T00:00:00+09:00

Quantum change point metrology arXiv · Oct 28, 2026The paper quantifies the extra Bayes risk of locating a quantum change point and estimating its amplitude with a single measurement when both parameters are unknown. It analyzes recovery conditions and cost scaling for ideal steps, finite offset prior width, and a quintic profile. It also examines a common optimum under quadratic position loss within the covariant class.

Hierarchical Quantum Optimization That Solves Problems Larger Than the Qubit Limit

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Symmetry-Preserving Hierarchical Quantum Approximate Optimization Algorithm with Subproblems Beyond the Qubit Limit arXiv · Oct 28, 2026This paper proposes symmetry-preserving hierarchical QAOA (SP-HQAOA), which uses parity sector contraction to keep the zero-field Ising structure of the objective at each step, so each quantum call uses at most Q qubits even when leaf blocks exceed Q. The authors give a deterministic bound on the optimal-value loss from each sector restriction, and these bounds can be summed across contraction steps and hierarchy levels. At depth p=1, the method reaches 99.4% to 99.7% of the exact optimum on 40-node random regular MaxCut leaf blocks, and 96% of a classical reference for N=500 using at most 10 qubits per circuit.

Einstein metrics and quantum control on a symmetric quotient of unitaries

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Einstein Metrics and Quantum Control on Symmetric Tensor Product Quotients arXiv · Oct 28, 2026The paper studies the quotient space M_n of projective n-qubit unitaries by local unitaries and qubit permutations. For sufficiently large n, it proves that M_n admits exactly two PU(2^n)-invariant Einstein metrics up to scaling. After normalizing two-qubit costs, both metrics have uniformly bounded diameter, even though approximating a Haar-random unitary requires exponentially many two-qubit gates.

Time evolution in multi-component dynamical Keldysh models, a study of how quantum systems evolve under long-correlated random noise.

2026-10-28T00:00:00+09:00

Time evolution in the multi-component dynamical Keldysh models arXiv · Oct 28, 2026The paper constructs a time evolution operator for dynamical quantum models driven by a multi-component random Gaussian field with a long correlation time. It analyzes three cases: a non-Abelian SU(2) symmetry class for three-component noise, and Abelian U(1) and Z2 classes for two- and one-component noise. The authors derive and solve coupled linear differential equations for exact diagonal and off-diagonal single-particle Green's functions, and use a continued fractions method to handle finite time correlations in Keldysh models.

Exact, Scalable Quantum Optimization Gradients from Strict Causal Light-Cone Frequency Bandwidths

2026-10-28T00:00:00+09:00

Strict Frequency Bandwidths from Causal Light Cones Enable Scalable Exact Gradient Evaluation in Quantum Optimization arXiv · Oct 28, 2026The paper shows that in layered quantum circuits built from commuting local terms, strict Heisenberg light cones limit energy slices to finite Fourier bandwidths when a shared layer parameter is varied. This allows exact gradient evaluation via a multipoint parameter-shift rule based on the discrete sine transform. For QAOA on bounded-degree graphs at fixed depth, the number of distinct circuit settings needed for the derivative drops from O(m) to O(1).

Reducing finite-copy precision bounds for multiparameter quantum estimation using Schur–Weyl symmetry

2026-10-28T00:00:00+09:00

Schurn̆icodex2013Weyl Reduction of Finite-Copy Precision Bounds for Multiparameter Quantum Estimation arXiv · Oct 28, 2026This paper studies the precision achievable in multiparameter quantum estimation with a finite number of jointly measured copies. It uses permutation symmetry of i.i.d. copies via Schur–Weyl duality to reduce the statistical model while preserving equivalence under collective measurements. On the reduced model, the authors derive an exact conic form of the tight Cramér–Rao bound and a semidefinite program for its Nagaoka–Hayashi relaxation. Numerical examples illustrate the quadratic scaling of the mesh correction and the computational reach of the formulation.

Maximally-matched mixture decoding for correlated atom loss in quantum LDPC codes

2026-10-28T00:00:00+09:00

Maximally-Matched Mixture Decoding for Correlated Atom Loss in Quantum LDPC Codes arXiv · Oct 28, 2026This paper addresses correlated atom loss at two-qubit gates in neutral atom quantum computers, where losing one atom often means losing its gate partner. The authors propose a maximal-matching-mixture (MMM) decoder that builds a per-readout decoding hypergraph from the maximum matchings of the graph of possible lost-qubit pairings. This hypergraph can be used with an ordinary belief-propagation decoder. On the [[144,12,12]] Gross code, MMM reduces the logical error rate by up to about 25x compared with a loss-unaware decoder and about 2x compared with the uniform-mixture baseline from Baranes et al. (2026).

Active method for fast quantum state preparation and reset in atomic arrays

2026-10-28T00:00:00+09:00

Active Approach to Fast Quantum State Preparation and Reset in Atomic Arrays arXiv · Oct 28, 2026This paper studies rapid preparation and reset of quantum states in a waveguide-coupled emitter array operating at low excitation. By decomposing the effective non-Hermitian Hamiltonian into biorthogonal modes, the authors link relaxation speed to overlap with subradiant modes, and propose local-drive protocols for reset and Dicke-state preparation. The reported reductions in time are up to about 25% for reset and 45% for preparation.

Noise propagation and effective channels in encrypted quantum cloning, a study of how errors spread through a quantum copying protocol.

2026-10-28T00:00:00+09:00

Noise Propagation and Effective Channels in Encrypted Quantum Cloning arXiv · Oct 28, 2026This paper studies how noise spreads in an encrypted quantum cloning protocol by describing the protocol through effective recovery channels. It shows that the effect of noise depends strongly on which qubit it acts on, for example turning isotropic depolarizing noise into an anisotropic recovery channel in one case. The authors conclude that effective recovery noise depends on the noise's physical location and the protocol's structure, not only on its strength.

Quantum advantage via designed beneficial dissipation from lossless dynamics

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Quantum advantage by designing beneficial dissipation from lossless dynamics arXiv · Oct 28, 2026This paper studies whether passive loss, designed from lossless quantum dynamics, can improve an unconditional target. It derives a trajectory-level criterion and builds a response operator from the lossless dynamics, whose spectrum shows whether weak passive loss helps and whose principal eigenvector gives the optimal environmental mode. Applied to vibronically assisted transfer, the predicted mode is near-optimal at finite loss, giving an 8.73% enhancement over the independently optimized lossless benchmark, versus 9.52% under full finite-loss optimization.

Experimental observation of a phase transition in error resilience on a superconducting quantum chip

2026-10-28T00:00:00+09:00

Experimental Observation of Error-Resilience Phase Transition on Superconducting Quantum Processor arXiv · Oct 28, 2026Random unitaries spread quantum information across nonlocal degrees of freedom, protecting it from local noise, but this protection fails once noise becomes strong enough. This paper reports the first experimental observation of this transition on IBM's ibm_pittsburgh Heron r3 device with up to 26 qubits. The transition is detected using fidelity, Rényi-2 entanglement entropy, and stabilizer Rényi-2 entropy, with zero-noise extrapolation and M3 error mitigation. The fitted critical angle is about 1.01, below the theoretical value of about 1.14.

A coherent neutron-nucleus hybrid system linked by the strong force

2026-10-28T00:00:00+09:00

A Coherent Neutron-Nucleus Hybrid System Mediated by the Strong Interaction arXiv · Oct 28, 2026This paper describes a neutron-nucleus hybrid system formed by coupling a coherent ensemble of polarized helium-3 nuclei with free neutrons. The nuclei are prepared in a spin superposition, and a magnetic field splits their energy levels, so the nuclear phase is coherently transferred to the neutron, producing an intensity beat at the nuclear Zeeman frequency. The incident neutron is prepared in a spin-energy superposition, and the nuclear and neutron phases heterodyne to give a signal at the sum or difference frequency depending on their relative helicity.

Telecom-band quantum dots on metamorphic InGaAs: coherent control and pure single-photon emission

2026-10-28T00:00:00+09:00

Coherent control and high purity single-photon emission from telecom quantum dots on metamorphic InGaAs arXiv · Oct 28, 2026This paper studies InAs quantum dots embedded in relaxed InGaAs matrices on metamorphic InGaAs layers, aiming for emission in the telecom O- and C-bands. By comparing quasi-resonant and phonon-assisted excitation schemes, the authors separate excitation effects from intrinsic emitter properties. They report linewidths as narrow as 21 μeV, the disappearance of slow decay channels, and single-photon purity with second-order autocorrelation values on the order of 10^-2. Rabi-like oscillations are observed in both telecom bands, suggesting potential for quantum technologies.

Exact positive-P simulation of open quantum spin systems using a generalized density matrix representation

2026-10-28T00:00:00+09:00

Exact Positive-P Simulation of Open Quantum Spin Systems with Generalized Density Matrix Formalism arXiv · Oct 28, 2026The paper proposes a phase-space representation that maps spin-1/2 degrees of freedom onto parameters of a local generalized density matrix (GDM) instead of SU(2) coherent states. In all stable regimes, the stable solutions match exact results up to stochastic sampling noise. The GDM approach combines with the bosonic positive-P representation to enable scalable simulation of coupled spin-boson systems, which is demonstrated on the Jaynes-Cummings model and a Jaynes-Cummings-Hubbard lattice.

Quantum key sharing over fading links with minimal eavesdropper leakage

2026-10-28T00:00:00+09:00

Continuous variable quantum key distribution through a fading channel with minimal information leakage arXiv · Oct 28, 2026This paper analyses a continuous variable quantum key distribution protocol over a fading channel, a model for free-space links. The protocol was previously shown to eliminate eavesdropper information in pure-loss channels and minimise it in noisy ones. The authors find that it keeps strong performance under fading and outperforms comparable protocols.

Sample Complexity of Generative Learning for Quantum Measurement Data

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Sample Complexity for Generative Learning of Quantum Measurement Data arXiv · Oct 28, 2026This paper presents a bias-variance framework for choosing model capacity when learning a quantum measurement distribution from finite data. It decomposes the expected population KL error into a representation bias term and a variance term, deriving four scaling templates for the optimal error. For transverse-field Ising Born distributions, the independently evaluated bias and estimation cost are used to predict the optimal context radius and optimal error, with power-law decay in N in gapped regimes and inverse-power decay in ln N at criticality.

Lowering the cost of purifying ancilla states for Majorana quantum computation

2026-10-28T00:00:00+09:00

Reducing the cost of ancilla purification for Majorana quantum computation arXiv · Oct 28, 2026The paper notes that braiding Majorana zero modes alone does not yield a universal gate set, so ancillary states are needed for extra operations. It adds an extra comparison layer to the purification of the non-Gaussian ancilla in Bravyi's scheme, so that the preparation error decreases cubically rather than quadratically. The authors also present a preliminary purification sequence and report a distillability fidelity under ideal operations.

Ontology without states: a dynamics-first realist argument from PBR

2026-10-28T00:00:00+09:00

Ontology without states: PBR as an argument for dynamics-first realism arXiv · Oct 28, 2026This paper examines the common reading that the PBR theorem shows a pure quantum state represents a physical property of the system, arguing this reading presupposes a state-first theory. It distinguishes state-first from dynamics-first physical theories and uses a recent interpretation of quantum theory as an example. The author shows a dynamics-first theory can explain the PBR correlations while keeping a broadly epistemic view of quantum states. The conclusion is that PBR poses a dilemma: either the quantum state is part of reality, or reality is not fundamentally made of states.

Are quantum measurements universal?

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Are quantum measurements universal? arXiv · Oct 28, 2026The paper revisits a 2014 result that the Born rule arises as a universal average over all ways of selecting measurement-interactions in an extended Bloch representation. In response to criticisms tied to Bertrand's paradox, it defines a universal measurement as one that is indifferent to any part of the interaction structure. It proves that every such indifferent universal measurement yields exactly the Born probabilities, with a unique average.

Geometry of quantum teleportation in phase space: a study describing the standard teleportation protocol using deformation quantization.

2026-10-28T00:00:00+09:00

The Geometry of Quantum Teleportation in Phase Space arXiv · Oct 28, 2026The paper formulates the standard quantum teleportation protocol within deformation quantization, using the Stratonovich–Weyl correspondence and star product on SU(2) coadjoint orbits. Each qubit is represented by a spherical phase space with the KKS symplectic structure. The authors construct phase space representations of the Bell resource, controlled-NOT and Hadamard operators, measurements, and conditional Pauli corrections, showing how the input qubit's Wigner function is redistributed through correlations and reconstructed at the receiver.

Quantum Foundations Beyond Bell's Theorem: A Topical Review

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Quantum Foundations Beyond Bell's Theorem: A Topical Review arXiv · Oct 28, 2026This review surveys recent no-go theorems that extend the methods and concepts of Bell's theorem to more complex operational settings, including independent sources, quantum networks, joint measurements, and multiple observers. The authors organize these results under a shared Bell-inspired methodology that goes beyond quantum nonlocality. They also show how richer operational structures change which physical assumptions can be tested.

Exact verification of rotation circuits for estimating iron-sulfur cluster quantum phases

2026-10-28T00:00:00+09:00

Exact verification of Givens rotation circuits for efficient quantum phase estimation of iron-sulfur clusters arXiv · Oct 28, 2026The paper addresses Givens rotation circuits, which account for much of the cost of published quantum phase estimation algorithms for iron-sulfur clusters. The authors propose an exact verification method that separates a fixed Clifford change of basis and tracks basis states and phases in the remaining circuit, using integer conditions to confirm correctness. Replacing only the rotation term lowers Toffoli counts by 9.5-14.3% on benchmarks including FeMoco, with the walk operator unchanged.

Estimating ground-state energy on cat qubits: FeMoco-54 in 23.5 hours with 7,164 qubits

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Ground-state energy estimation compiled on cat qubits: 7 164 qubits for FeMoco-54 in 23.5 hours arXiv · Oct 28, 2026This paper presents a detailed resource estimate for the sum-of-squares block encoding algorithm of Low et al. applied to electronic structure Hamiltonians, compiled for superconducting cat qubits. It gives closed-form costs for key subroutines and global layouts for repetition-cat and LDPC-cat architectures, combined with adder compilation from a companion work. Under stated assumptions, the authors report that FeMoco-54 needs fewer than 7,500 cat qubits with an expected runtime under one day per phase estimation run on the LDPC-cat architecture.

Running Shor's factoring algorithm on cat qubits: resource estimates for breaking RSA-2048

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Shor's algorithm compiled on cat qubits: 22 593 qubits for RSA-2048 in 3.14 days arXiv · Oct 28, 2026This paper gives an end-to-end resource estimate of Shor's algorithm on superconducting cat qubits, covering the mathematical description through physical qubit allocation and scheduling on a chip layout. The authors compile the main subroutines onto two architectures, one based on repetition cat codes and one on LDPC cat codes, and design primitives such as a parity-CNOT gate for cat qubits. Under stated assumptions of error-correction cycle time, reaction time and phase-flip noise, factoring RSA-2048 requires about 23,000 cat qubits and 3.14 days.

Stellar Representation of GKP States on the Double Discrete Cylinder

2026-10-28T00:00:00+09:00

Stellar Representation of Gottesman Kitaev Preskill States on the Double Discrete Cylinder arXiv · Oct 28, 2026This paper develops covariant integral quantization on a double discrete cylinder phase space with the torus as configuration space, yielding a Wigner distribution and a stellar representation. The phase space suits translationally invariant states such as Gottesman-Kitaev-Preskill (GKP) states, which are central to fault-tolerant quantum computing. It compares zeros of the stellar representations of ideal GKP logical states and their superpositions, and examines how zeros of the vacuum and finitely squeezed GKP states move with peak and envelope widths.

Exact Solutions for a Dunkl-Klein-Gordon Oscillator in Non-Commutative Phase Space with a Magnetic Field

2026-10-28T00:00:00+09:00

Exact Solution of the (2+1)-Dimensional Dunkl-Klein-Gordon Oscillator with a Uniform Magnetic Field in Non-Commutative Phase Space arXiv · Oct 28, 2026This paper solves a generalized Klein-Gordon oscillator, built with Dunkl derivatives, in non-commutative phase space, both with and without a uniform magnetic field. The authors use the Seiberg-Witten map to extend the commutative system and obtain exact eigenfunctions and energy spectra, which correspond to generalized Landau levels when a field is present. They also compute the non-relativistic limit and show that the solutions reduce to earlier commutative Dunkl models when the field or non-commutative parameters vanish.

Complex Langevin kernels for real-time SU(N) lattice gauge theory simulations in 3+1 dimensions

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Complex Langevin kernels for real-time SU(N) lattice gauge theory in 3+1 dimensions arXiv · Oct 28, 2026This paper studies complex Langevin dynamics for real-time SU(N) gauge theories in 3+1 dimensions and introduces new kernel modifications for lattice gauge theory. Using the anisotropic kernel as a baseline, stable simulations of pure SU(2) gauge theory at bare coupling g=0.5 reach a real-time extent of 2β on a rectangular regularized Schwinger-Keldysh contour. A local, field-dependent kernel based on traced plaquettes extends this to 3.5β. The authors also generalize the drift-magnitude correctness criterion to kernelled dynamics.

Parity-resolved many-body dynamics of a topological qubit hit by phonon pulses

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Parity-Resolved Many-Body Kinetics of a Topological Qubit under Nonequilibrium Phonon Pulses arXiv · Oct 28, 2026This paper studies how phonon bursts from ionizing radiation affect a Majorana qubit made of two 2-micrometer proximitized nanowires, causing excitation, relaxation, and loss of logical coherence. The authors combine a lattice Lutchyn-Oreg model, microscopic electron-phonon coupling, and parity-resolved many-body dynamics. They find that even without quasiparticle escape, phonons can retain logical-state information, leaving permanent coherence loss.

Error thresholds of a new symmetry-enriched toric quantum code

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Topological Quantum Error-Correcting Thresholds of a Symmetry-Enriched Toric Code arXiv · Oct 28, 2026This paper studies the error thresholds of a new topological quantum error-correcting code under independent bit-flip and phase-flip noise. By mapping the problem to classical spin-glass models, the authors find that with equal X and Z error probabilities, the vertex-syndrome threshold improves by 30% over the toric code while the plaquette-syndrome threshold decreases. Both thresholds rise when Z errors are less likely than X errors, reaching 0.5 when Z errors are absent.

Entanglement measures and LOCC conversion criteria via Schur-Weyl duality

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Entanglement measures and LOCC conversion criteria from Schur-Weyl duality arXiv · Oct 28, 2026This paper presents a method to optimize functions of the entanglement spectrum of bipartite states over mixed-state decompositions to arbitrary accuracy. The approach uses a convergent semidefinite programming hierarchy based on a polynomial basis and Schur-Weyl duality. It also computes non-polynomial measures such as the entanglement of formation and characterizes the dimensionality of entanglement. The authors further provide a hierarchy of certificates for LOCC non-convertibility from pure to mixed states, along with a heuristic for LOCC convertibility.

Magic in Grover's Algorithm and the Role of Oracle Synthesis: a study of how the quantum resource called non-stabilizerness grows during Grover's search algorithm.

2026-10-28T00:00:00+09:00

Magic in Grover's Algorithm and the Role of Oracle Synthesis arXiv · Oct 28, 2026This paper studies the non-stabilizerness, or "magic," that builds up during Grover's quantum search algorithm, measured relative to stabilizer states that classical computers can simulate efficiently. The authors derive an analytic prediction for the stabilizer Rényi entropy after each Grover iteration and show it stays intensive as system size grows. They also examine the extra magic introduced when circuits are decomposed into elementary gates, and check the case of the 3-SAT problem.

Long-range toric code models that keep finite-temperature topological order in 2D

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Long-Range Toric Code: Finite-Temperature Topological Order in Two Dimensions arXiv · Oct 28, 2026The paper introduces two-dimensional toric code models with added long-range loop interactions. These models keep the topologically ordered ground states of the ordinary toric code while confining anyons at zero temperature. For sufficiently long-range interactions, the authors argue this confinement persists at finite temperature, giving finite-temperature topological order that acts as a self-correcting quantum memory. For shorter-range interactions, topological order signatures survive only up to an exponentially large length scale, yielding a partially self-correcting quantum memory.

Lattice definition of 2-group symmetries and extraction of their anomalies

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Defining 2-group symmetries on lattices and extracting their anomalies arXiv · Oct 28, 2026Ordinary 0-form symmetries can combine with 1-form symmetries to form a 2-group. The paper gives a concrete lattice definition for a class of finite 2-group symmetries using local relations among symmetry operators, which identify the Postnikov class that characterizes the mixing. It develops a method to extract anomalies in one spatial dimension by restricting symmetry operations to an interval and comparing their composition near the endpoints. Explicit qubit symmetry actions for a 2-group with G=Π₂=Z₂ are constructed in one, two, and three spatial dimensions.

Barren plateaus in quantum linear combinations: interference and Lie-algebra control

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Barren Plateaus in Quantum Linear Combinations: Interference and Lie-Algebraic Control arXiv · Oct 28, 2026This paper studies how interference from coherently summing quantum circuits, known as linear combinations of unitaries (LCU), affects the training signal. For a single-pass LCU, the authors show that even when each branch has zero matrix mean, the total gradient variance is at least the branch variance times the fourth power of its coefficient magnitude. They also derive exact loss and gradient formulas for interference between branches, with a four-qubit matchgate example where the interference term is nonzero.

A perspective paper on AI and quantum open-source software

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Perspective on AI and quantum open-source software arXiv · Oct 28, 2026This paper examines how verification is needed for reliable AI-assisted quantum software development. The authors analyze public repositories, records from 110 repositories across five quantum open-source hackathons, and a survey of more than 1,600 participants. They propose verification practices and contribution standards requiring reproducible evidence, and discuss how quantum open-source software can support independently verifiable AI-driven research.

Twisted Fourier analysis of quantum weight enumerators for quantum codes

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Twisted Fourier Analysis of Quantum Weight Enumerators arXiv · Oct 28, 2026This paper builds a unified Fourier framework for quantum weight enumerators of prime-power-dimensional qudits, introducing Weyl power spectrum and Weyl-conjugation autocorrelation as a symplectic Fourier pair that yields the quantum MacWilliams identity. The framework extends to twisted Fourier transforms, including the Rains shadow transform, and shows that all such twists reduce to Weyl translations of two basic transforms. Using refined identities in linear programming, the authors obtain tighter bounds for binary and qutrit quantum codes, including nonexistence results for certain parameters.

A lower bound on the region of non-distillable magic states

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Lower Bound for Region of Non-Distillable Magic States arXiv · Oct 28, 2026This paper studies magic states, a leading approach to fault-tolerant universal quantum computation. It extends the proof of Campbell and Browne on bound magic states. The authors determine a lower bound on the region of states outside the stabilizer octahedron that cannot be used to achieve universal computation.

Adiabatic tracking and optimal schedules for preparing Gibbs states on classical and quantum computers

2026-10-05T00:00:00+09:00

Adiabatic tracking and geometric schedules for classical and quantum Gibbs-state preparation arXiv · Oct 5, 2026This paper presents a discrete adiabatic framework for preparing Gibbs states in classical and quantum optimisation algorithms. It proves a tracking theorem for time-inhomogeneous reversible Markov chains and derives schedules adapted to the spectral gap and energy fluctuations. Applying the discrete quantum adiabatic theorem to temperature-dependent Szegedy quantum walks, the authors state that under suitable regularity conditions the quantum cost scales as O(δ_min^{-1/2}), versus the classical O(δ_min^{-1}).]

Exact analytical solution for collectively pumped superradiance in Dicke states

2026-10-28T00:00:00+09:00

Exact Analytical Treatment of Collectively Pumped Dicke Superradiance arXiv · Oct 28, 2026This paper studies a group of N two-level emitters that decay collectively and are pumped collectively, staying within the symmetric Dicke states. The authors sum up the infinitely many quantum trajectories created by competing pumping and decay to obtain an exact finite continued fraction for the Dicke-state populations. They also give perturbative transient solutions for strong and weak pumping, along with relaxation eigenvalues and emission observables for balanced pumping and decay.

Optimal quantum discrimination at Liouvillian exceptional points

2026-10-28T00:00:00+09:00

Optimal quantum discrimination at Liouvillian exceptional points arXiv · Oct 28, 2026This paper examines whether exceptional points (EPs) in non-Hermitian systems help detect weak perturbations. In finite-dimensional Lindblad systems with a unique stationary state and nonzero relaxation gap, the authors show EPs give no fundamental advantage in how observation time scales with perturbation strength. However, by selecting perturbations that boost the quantum Fisher information rate, EPs can reach a set detection accuracy faster than a non-EP reference with the same decay rate. An optomechanical model illustrates detecting a weak force at an EP in less time.

Repulsive Landau Interactions Between Fermi Polarons at Strong Coupling

2026-10-28T00:00:00+09:00

Mediated Interactions between Fermi Polarons in the Strongly Interacting Regime arXiv · Oct 28, 2026This paper studies mediated interactions between quasiparticles emerging from a Fermi sea, known as Fermi polarons, using zero-temperature quantum Monte Carlo methods. The main result is that the Landau interaction between polarons stays repulsive across all coupling strengths on the polaronic branch in the strongly interacting regime. The authors also compute the real-space interaction between static impurities, which shows RKKY-like behavior at weak coupling and matches the nonperturbative Born-Oppenheimer result at strong coupling. ★★★★ Notable: The authors use zero-temperature quantum Monte Carlo to study mediated interactions between Fermi polarons, reporting that the Landau interaction stays repulsive at strong coupling, unlike the downwar

Dynamical quantum simulations used as testbeds for quantum information

2026-10-28T00:00:00+09:00

Dynamical quantum simulations as laboratories for quantum information arXiv · Oct 28, 2026This paper shows that dynamical quantum simulations built to compute response functions prepare many-body states that carry information beyond their original observable. Using local-pulse protocols for Green functions in finite XX and XXX spin chains as a case study, the authors encode a classical bit via opposite source rotations and track how this record spreads across local subsystems and how readily different measurements access it. They find that fermionic covariance reconstructs the signed response in the XX chain, while simple spin measurements recover more local information in the XXX chain. The analysis is extended to Bell state recovery, quantum communication rates, and bipartite and multipartite entanglement.

Meet-in-the-Middle Compilation of the [CNOT] Class with Fibonacci Anyons

2026-10-28T00:00:00+09:00

Meet-in-the-Middle Compilation of the [CNOT] Class with Fibonacci Anyons arXiv · Oct 28, 2026This paper studies how to compile two-qubit gates for Fibonacci anyons, where errors arise from leakage out of the computational subspace into a fifth fusion state. The authors build a GPU pipeline that searches braid group subsets for low-leakage representatives of the [CNOT] class, narrowing the search space to reach braid length L=72. They prove that leakage lies in Z[φ], that nonzero leakage has an exponential lower bound in braid length, and derive limit distribution laws.

Recovering classical gauge geometry from quantum master constraints

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Recovering classical gauge geometry from quantum master constraints arXiv · Oct 28, 2026The paper asks how the degenerate directions of classical first-class constraints can be recovered when quantum theory is taken as fundamental and the constraints are imposed through a single positive master operator. For a nonnegative master function whose zero set is a Morse–Bott critical manifold, the image of the linearized Hamiltonian vector field is shown to be the symplectic orthogonal of the zero set, with coisotropy equivalent to the linearization having square zero. Three realizations are discussed, including the spectral bottom for quadratic masters and results for the non-Abelian SL(2,R) model.

Adaptive Information Mining: Reaching the Quantum Limit of Super-Resolution Imaging

2026-10-28T00:00:00+09:00

Adaptive Information Mining: Approaching the Quantum Limit of Super-Resolution Imaging arXiv · Oct 28, 2026This paper presents Adaptive Information Mining (AIM), a framework that achieves super-resolution by refining measurements of incoming photons in sequence. A reconfigurable imaging system reshapes its measurement responses to maximize Fisher information. When imaging point sources, the authors report estimation errors 2 to 5 times closer to the fundamental quantum limit than traditional direct imaging.

Paper on homodyne-based tracking and parameter estimation for quantum systems in squeezed thermal baths.

2026-10-28T00:00:00+09:00

Homodyne Unravelling and Parameter Estimation in Squeezed Thermal Baths arXiv · Oct 28, 2026The paper derives an alternative stochastic master equation for quantum systems continuously measured by homodyne detection in a squeezed-thermal environment. This form identifies two collapse operators for monitored and unmonitored channels and expresses state evolution through Kraus-like operators, aiding numerical methods and Cramér-Rao bound evaluation. For qubit frequency estimation, the authors compute the Fisher information of continuous homodyne monitoring and find that its steady-state rate still scales exponentially with squeezing at nonzero temperature.

Measurement incompatibility and noiseless quantum codes: a theory paper on whether quantum channels can preserve measurement incompatibility

2026-10-27T00:00:00+09:00

Measurement incompatibility and noiseless quantum codes arXiv · Oct 27, 2026The paper studies when a quantum channel universally preserves the incompatibility of measurements. The authors construct a rank-one minimal informationally complete measurement and prove that such preservation holds if and only if the input space contains a noiseless code subspace of full output dimension. They also give an explicit construction of exact encodings and connect the results to quantum steering and quantum error correction. ★★★★ Notable: The authors construct a rank-one MIC with invertible dual operator and claim that a channel universally preserves measurement incompatibility iff its input space contains a full-output-dimension noise

Security analysis of an Ekert-type QKD protocol under cloning attacks

2026-10-27T00:00:00+09:00

Security Analysis of Ekert-type QKD Protocol Coming Under Cloning Attacks arXiv · Oct 27, 2026This paper analyzes the security of an Ekert-type bipartite key distribution protocol when an untrusted observer performs cloning attacks. An eavesdropper intercepts qubits sent over a public channel and applies an asymmetric, phase-variant cloner to one or both of them. The authors partially characterize two-qubit states and use the Devetak-Winter framework to compute key rates, identifying states from which a secret key can still be distilled under such attacks.

Quantum key distribution secured by a bound on information leakage

2026-10-27T00:00:00+09:00

Prepare-and-measure quantum key distribution from a bound on information leakage arXiv · Oct 27, 2026This paper examines whether, in prepare-and-measure quantum key distribution, a single bound on information leakage from the sender's source can replace a detailed model of the source. The authors show that this bound, quantified by the probability of guessing the input from everything the source emits, suffices to prove security against collective attacks, with no assumptions on the form, dimension, energy or purity of the emitted states. They note that the standard B92 and BB84 protocols cannot certify a key under this assumption, whereas closely related protocols can reach one secret bit per round in the ideal limit. For noisy implementations, key rates are computed with semidefinite programming relaxations, and the best protocols tolerate visibilities down to 0.84, corresponding to an 8% quantum bit error rate, versus the 11% threshold of device-dependent BB84. ★★★★ Notable: Proposes security proofs from only a sender-side leakage bound, without modeling the source; the authors report one key bit per round ideally and tolerance down to visibility 0.84.

Experimental evidence that quantum Brownian motion drives electron decoherence in metals

2026-10-27T00:00:00+09:00

Experimental evidence for quantum Brownian motion in electron-metal decoherence arXiv · Oct 27, 2026This paper reports experiments showing that quantum Brownian motion plays a key role in the decoherence of electron motion. The authors observe clear signatures of electron-metal decoherence for the first time and show it can be continuously tuned. Agreement between experiment and theory is quantitative, which the authors say paves the way for testing the Caldeira-Leggett dissipation theory with free electrons.

Field-deployed entanglement-based BBM92 quantum key distribution using quantum-dot photons converted to telecom wavelengths

2026-10-27T00:00:00+09:00

Deployed entanglement-based BBM92 quantum key distribution using frequency-converted photons emitted by a quantum dot arXiv · Oct 27, 2026This paper uses a quantum dot to generate polarization-entangled photon pairs at a 1 GHz excitation rate, then converts them to telecom wavelengths while preserving entanglement. The researchers ran BBM92 quantum key distribution over a 1.59 km field-deployed fibre link at the University of Stuttgart's Vaihingen campus. Over 19 hours of stable operation they achieved a secure key rate of 206 Hz and a total secure key length of 14.2 Mbit, which was used to encrypt and decrypt a colour image.

HTM: A Hybrid Model Combining Classical and Quantum Computing

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HTM: A Hybrid Classical-Quantum Computation Model arXiv · Oct 27, 2026This paper addresses the lack of a unified hybrid model for collaborative classical and quantum computation. It proposes HTM, a hybrid classical-quantum computation model built on unified state sets and transition function representations. The model clarifies hybrid control logic, implements a control-sharing mechanism, and introduces a complexity calculation method based on entanglement and superposition to support task partitioning and resource scheduling.

QNETSIM: A Simulator for Designing Satellite and Hybrid Quantum Networks with Memory

2026-10-27T00:00:00+09:00

QNETSIM for memory assisted design of satellite and hybrid quantum networks arXiv · Oct 27, 2026The paper introduces QNETSIM, a modular discrete-event simulator for designing and evaluating satellite and hybrid space-ground quantum networks. It combines orbital geometry, free-space optical and fiber channels, quantum memories, entanglement generation, and Bell-state measurements in one event-driven framework. The simulator models optical loss, atmospheric turbulence, detector imperfections, finite memory capacity, and storage decoherence. It links these components to entanglement fidelity, throughput, latency, availability, and memory utilization.

Threshold conditions for boson and fermion three-body bound states on a square lattice

2026-10-27T00:00:00+09:00

Threshold Criteria for Bosonic and Fermionic Trimers on a Square Lattice: A Birman--Schwinger Comparison arXiv · Oct 27, 2026The paper compares two three-particle models on a square lattice at zero total quasimomentum: three identical bosons with attractive contact interactions, and two fermions plus one distinguishable particle with attractive interspecies contact. It uses the Birman–Schwinger principle with symmetry reduction and strong-coupling asymptotics to separate shared methods from model-specific spectral results. For bosons, exactly two bound states lie below threshold at large coupling, the second being a true eigenvalue 0.03542 below threshold. For fermions, the critical mass ratio is π/(π−2), about 2.75194, above which a doubly degenerate level appears at strong coupling.

Quantum generative model that trains only a linear output layer, not the circuit

2026-10-27T00:00:00+09:00

Generative quantum extreme learning machines arXiv · Oct 27, 2026The paper proposes a quantum generative method that encodes a random latent vector into a quantum state, applies a fixed unitary and measures, training only a linear output layer so the circuit itself is never trained. Using Pauli propagation, the authors show that Clifford circuits do not create new functions, while Haar-random brickwork circuits have features whose variation with the latent variable decreases with depth. Across one- and two-dimensional distributions, entangling reservoirs do not systematically improve the generator, and a reservoir with no gates performs competitively.

Time needed to confirm weak-force entanglement between levitated particles

2026-10-27T00:00:00+09:00

Certification Time for Weak-Force-Mediated Entanglement between Levitated Particles arXiv · Oct 27, 2026This paper studies how to certify motional entanglement generated by weak forces between levitated nanoparticles using finite, noisy measurement records. The authors derive a lower bound on the number of measurements needed to certify Gaussian entanglement and translate it into certification time. They compare release-recapture and continuous monitoring protocols, finding that release-recapture enables certification at interaction strengths several orders of magnitude weaker.

Quantum Fisher information deficit as a geometric sign of strong-to-weak symmetry breaking

2026-10-27T00:00:00+09:00

Quantum Fisher Information Deficit as a Geometric Signature of Strong-to-Weak Spontaneous Symmetry Breaking arXiv · Oct 27, 2026The paper studies strong-to-weak spontaneous symmetry breaking (SW-SSB), a phase of open quantum systems that conventional charged two-point correlators cannot detect. For strongly Z2-symmetric states with local charged involutions, the authors show that SW-SSB appears as a persistent gap between the quantum Fisher information and its maximum under symmetry-neutral pair rotations. This deficit is shown to be equivalent to fidelity and Rényi-1 correlator diagnostics of asymptotic long-range order, and a lower bound is derived for symmetry-projected Gibbs states.

Exact decoherence of a detector in bounded vacuum geometries

2026-10-27T00:00:00+09:00

Exact decoherence dynamics of a detector coupled to vacuum fluctuations in bounded geometries arXiv · Oct 27, 2026This paper studies how a two-level detector coupled to a vacuum scalar field loses coherence over time in three settings: free space, a single perfectly reflecting boundary, and a cavity between two parallel reflecting boundaries. The authors derive an exact decoherence function for the detector. Coherence decays monotonically in free space, partially persists with one boundary, and oscillates with a larger surviving fraction inside the cavity. The results suggest that boundary conditions can be used to engineer quantum coherence.

Using quantum annealing to detect and locate gamma-ray sources in AGILE data

2026-10-27T00:00:00+09:00

Quantum Annealing for Gamma-ray Source Detection and Localization with AGILE Data arXiv · Oct 27, 2026This paper reformulates maximum-likelihood gamma-ray source detection and localization as a Quadratic Unconstrained Binary Optimization (QUBO) problem and solves it with simulated quantum annealing. The method is applied to simulated observations from AGILE's Gamma-Ray Imaging Detector in the 30 MeV to 50 GeV band, generated with AGILEpy. The flux and position estimates agree with classical results within statistical uncertainty, and the correct grid node is identified in 97% of the maps.

Making the TEMPO network independent of system size

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The TEMPO network can be made independent of the system size arXiv · Oct 27, 2026The TEMPO method simulates non-Markovian open quantum system dynamics by contracting a two-dimensional tensor network. The paper shows that, within the usual second-order time-step error, all internal bond dimensions can be reduced to (2m+1)(m+1), where m is the number of independent coupling channels. This dimension does not depend on the number of distinct eigenvalues of the coupling operators. System size enters only through the final boundary layer, making large systems accessible to TEMPO.

Quantum entanglement in momentum space after Kaluza-Klein reduction

2026-10-27T00:00:00+09:00

Momentum-space entanglement and mutual information in Kaluza-Klein reduction arXiv · Oct 27, 2026This paper studies how a four-dimensional observer's reduced state, obtained by tracing out massive Kaluza-Klein modes of a five-dimensional scalar with cubic or quartic self-interaction, is entangled in momentum space. At leading order in the coupling, it computes the mutual information between low-energy zero modes and a single Kaluza-Klein level, finding a tail that falls as one over the level mass in the cubic theory. The authors conclude that the local four-dimensional effective theory describes low-energy observables but not the state of the reduced system.

Quantum and Classical Memory Needed to Store and Retrieve Quantum Measurements

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Quantum and Classical Memory for Storage and Retrieval of Quantum Measurements arXiv · Oct 27, 2026This paper studies how much persistent quantum and classical memory is needed to store and retrieve quantum measurements exactly and with heralding. Assuming only black-box access to the measurement channel, the authors compress a port-based program into an outcome-type record and a quantum register whose total dimension grows polynomially with the number of queries. For n-outcome POVMs on C^d with d ≥ 2, they prove lower bounds Q+C ≥ log₂n and 2Q+C ≥ log₂((n−1)d²+1) on the qubits Q and bits C of any retrieval program.

From QCCD trapped-ion hardware to quantum compilers: architectures and compilation methods

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From QCCD Trapped-Ion Hardware to Quantum Compilers: Capabilities, Architectures, and Compilation arXiv · Oct 27, 2026This paper examines shuttling-based trapped-ion quantum computers (QCCD) and their compilers, abstracting QCCD architectures and native operations so that computer scientists can address compilation problems without deep knowledge of the platform's physics. The design space is organized into a few architectural archetypes, and compilation methods are applied to one- and two-dimensional QCCD architectures. Routing overhead is found to scale roughly cubically with qubit number in one dimension and roughly quadratically in two dimensions. The authors also compare physical and logical levels when a quantum error-correction layer is added, and conclude that hardware-software co-design is required.

Correlation-sensitive magic-state distillation from spin-squeezed neutral atoms

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Correlation-sensitive magic-state distillation from spin-squeezed neutral atoms arXiv · Oct 27, 2026The paper shows that correlations between blocks can reverse magic-state distillation gain even when each input exceeds the independent-state threshold. Using the five-to-one Bravyi-Kitaev protocol, it expresses the output through measurable target-axis moments and gives a direct sign test for gain. It links this mechanism to neutral-atom resource preparation via finite-range Ising dynamics.

Entanglement between a qubit and its environment during pure dephasing when the qubit starts mixed

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Qubit-environment entanglement in pure dephasing dynamics for mixed initial states arXiv · Oct 27, 2026The paper studies entanglement between a qubit and its environment under interactions that cause pure dephasing, allowing the qubit's initial state to be mixed. The authors find that separability criteria valid for pure initial states reduce to entanglement witnesses in this setting. Using a spin qubit coupled to a sparse spin environment as an example, they illustrate the evolution of entanglement and note that witnesses are numerically more practical for large environments.

Open effective field theories: a framework for noisy, dissipative environments in gravity and cosmology

2026-10-27T00:00:00+09:00

The Disordered Universe 2025: Open Effective Field Theories arXiv · Oct 27, 2026These are lecture notes on Open Effective Field Theories, based on lectures given at the La Ricotta Summer School "The Disordered Universe 2025". The text notes that traditional effective field theories were developed for particle physics with clean, isolated initial states, while realistic environments are often noisy and dissipative. It presents an approach that models the gravitational sector as evolving in the presence of an unobservable medium, and uses the Schwinger-Keldysh formalism to show how unknown environments appear as dissipation and noise in observational probes.

A unified six-step protocol for arbitrary Z rotations on a class of bosonic cQED qubits

2026-10-27T00:00:00+09:00

A Unified Protocol for Arbitrary Z Rotations of a Class of Bosonic cQED Qubits arXiv · Oct 27, 2026This paper examines a class of bosonic Fock-based qubits in circuit QED and shows that different ways of implementing arbitrary Z rotations on them share a common structure. The authors formulate this structure as a six-step protocol that gives a unified procedure for arbitrary Z rotations across this qubit class. Whether the protocol applies depends on a specific condition on the encoding, which serves as a criterion for identifying which bosonic Fock-based cQED qubits admit this common implementation.

Storing and extracting energy in V-type quantum batteries via dark states

2026-10-27T00:00:00+09:00

Controlled Dark-State Energy Storage and Work Extraction in V-Type Quantum Batteries arXiv · Oct 27, 2026This paper studies a quantum battery made of V-type qutrits coupled to a lossy cavity. A finite splitting pulse converts cavity-bright excitations into atomic dark states, which keep their stored energy even after degeneracy is restored. The authors also bound the passive energy in the symmetric atomic subspace and compare coherent and Fock initial states for finite-time ergotropy and extractable work.

Quantum state preparation for complex amplitudes

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Quantum State Preparation for Complex-Valued Amplitudes arXiv · Oct 27, 2026This paper presents a procedure that prepares a quantum amplitude approximating z/α for a complex number z=x+iy, starting from registers holding its real and imaginary parts, with α a normalization constant. It computes the magnitude and argument with the CORDIC algorithm, encodes the magnitude into an amplitude, and applies phase gates for the argument. The method uses O(n²) T gates and O(n) extra qubits. Compared with encoding real and imaginary parts separately and combining them via LCU, it can allow a smaller normalization and reduce amplitude-amplification costs.

Diagnostic-dependent lasting Mpemba effect in a parametrically driven oscillator

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Diagnostic-dependent lasting Mpemba effect in a parametrically driven oscillator arXiv · Oct 27, 2026This paper studies relaxation of two Gaussian states in a detuned degenerate parametric amplifier below threshold. The trace distance shows a lasting Mpemba reversal, while relative entropy eventually restores the initial order and Hilbert-Schmidt distance alternates indefinitely. The three diagnostics agree on the initial order but can disagree because a real mode and a complex pair share the leading decay rate.

Kinetic Slush in Dissipative Rydberg Arrays: a nonequilibrium soft-matter state in driven atom arrays

2026-10-27T00:00:00+09:00

Kinetic Slush in Dissipative Rydberg Arrays arXiv · Oct 27, 2026The paper studies a kinetic slush state in a two-dimensional dissipative Rydberg atom array, where excitations are facilitated by neighboring atoms. Using kinetic Monte Carlo simulations in the strong dephasing regime, the authors show that detuning compensates nearest-neighbor interactions, while residual next-nearest-neighbor interactions create kinetic frustration. The competition yields a slush phase with liquid- and solid-like configurations and strong dynamical heterogeneity.

Noise thresholds for reliable quantum approximate optimisation under noise

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Effective Noise Thresholds for Reliable Quantum Approximation Optimisation Algorithm under Noisy Environment arXiv · Oct 27, 2026This paper studies how much noise the quantum approximate optimisation algorithm (QAOA) can tolerate at each circuit depth. The authors run GPU-accelerated noisy simulations on MaxCut for three graph families and fit approximation ratios with a generalised logistic surface. They define an effective noise threshold, which generally decreases as depth increases, and use it to separate reliable from unreliable noise regimes.

Measurement-induced entanglement phases in hyperbolic gauge-Higgs models

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Measurement-induced entanglement phases in hyperbolic gauge-Higgs models arXiv · Oct 27, 2026This paper studies entanglement phases of gauge-Higgs models on hyperbolic lattices, described by measurement-only dynamics. The authors map two-dimensional phase diagrams using topological entanglement entropy and a generalized measurement-induced entanglement suited to hyperbolic Higgs phases. They identify an "archipelago" phase absent in Euclidean space, where separated clusters of symmetry-protected topological order exist, and its transitions have mean-field critical exponents.

Fewest Measurement Settings for Estimating Several Quantum Observables

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Minimal Projective Measurement Settings for Estimating Multiple Observables arXiv · Oct 27, 2026This paper studies the minimum number of orthogonal projective measurement settings needed to estimate several observables without bias for any input state. The authors derive structural lower bounds beyond dimension counting and give explicit constructions that certify minimum setting counts for chosen target spaces. A classical variational algorithm searches for shared measurement bases and optimizes readout coefficients and sample allocation. For the collective first and second moments of two qubits, four projective settings are shown to be both necessary and sufficient.

Unusual shapes of Fisher zero lines in biorthogonal dynamical quantum phase transitions

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Anomalous Structures of Fisher Zero Lines in Biorthogonal Dynamical Quantum Phase Transitions arXiv · Oct 27, 2026This paper studies how Fisher zero lines of the Loschmidt amplitude in non-Hermitian quenches can form unusual patterns in the complex time plane, such as divergence, separation, or branches lying on the real or imaginary axis. It uses a biorthogonal framework to explain these patterns and sets critical momentum conditions based on the dot product of normalized prequench and postquench complex Bloch vectors. The results are verified in a generalized non-Hermitian SSH model, and Jordan form is used to analyze dynamics at postquench exceptional points.

Dynamical behaviour of the mass tensor in the lattice

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Dynamical behaviour of the mass tensor in the lattice arXiv · Oct 27, 2026This paper studies, with a semiclassical model, how a particle hopping through an orthorhombic lattice moves under a static Coulomb field and a rapidly oscillating homogeneous field. Applying the oscillating field reparameterizes the effective masses so they become equal in both directions, turning a chaotic trajectory into an elliptic one in the continuum limit, as confirmed by Lyapunov exponents. The authors also show that an external magnetic field along the Z direction can control chaos, and extend the scheme to three-dimensional trajectories.

Coherent optical control of a single donor electron spin

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Coherent Optical Control of a Single Donor Electron Spin arXiv · Oct 27, 2026This paper demonstrates optical initialization, coherent control, and readout of a single donor-bound electron spin in ZnSe. Using spin-selective donor-bound exciton transitions and off-resonant picosecond pulses, the authors observe spin Rabi oscillations, Ramsey interference, and high-contrast coherent population trapping. At higher driving strengths, multiple dark resonances reveal the hyperfine interaction with the I = 3/2 Cl nucleus, and the authors identify isolated optical donors as a promising platform for solid-state optically active qubits. ★★★★ Notable: The authors report optical initialization and coherent control of a single donor electron spin in ZnSe, with coherent population trapping and hyperfine interaction with the Cl nucleus revealed by mult

Analytic energy formulas for radial power-like potentials via new Bohr-Sommerfeld quantization conditions

2026-10-27T00:00:00+09:00

Radial power-like potentials: from the Bohr-Sommerfeld ℓ ≠ 0 state energies to the exact ones arXiv · Oct 27, 2026The paper proposes two new Bohr-Sommerfeld type quantization conditions for d-dimensional radial singular and non-singular potentials. It studies power-like potentials and the logarithmic potential across many radial quantum numbers and angular momenta in dimensions two and three. For large radial quantum numbers the approximate energies approach the exact ones, and a dimensionless WKB correction reproduces exact energies within the cases examined.

Sideways position shift of a spinning particle's wave packet under Lorentz boosts

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Side jump and anomalous Lorentz transformation of a coherent Dirac wave packet arXiv · Oct 27, 2026This paper studies how spin-orbit coupling makes the average position of a spinning particle shift unusually under a Lorentz boost, an effect called a side jump. The authors develop a trace method that yields an exact, compact transformation kernel for the probability center of a general three-dimensional Dirac wave packet under any finite boost, without a semiclassical expansion. They find that side jumps depend on the wave packet's internal structure and that, for Gaussian packets, they show a non-monotonic dependence on mass.

Consensus and information spreading in quantum networks: how nodes learn global quantum information from local measurements

2026-10-27T00:00:00+09:00

Consensus And Information Redistribution In Quantum Networks arXiv · Oct 27, 2026This paper studies decentralized quantum consensus in qudit networks evolving under discrete random unitary dynamics. The authors analyze asymptotic behavior, identify global information preserved by the evolution, and give conditions under which different forms of quantum consensus arise. They present a general theorem for extracting globally encoded information from local measurements, examine CNOT networks, and identify two-qubit interactions that asymptotically reach consensus on average excitation number.

Finite-temperature quantum theory of lossy magnon-cavity resonators

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Finite-temperature Quantum Quasinormal Mode Theory for Spatiotemporally-resolved Dissipative Cavity Quantum Magnonics arXiv · Oct 27, 2026This paper develops a finite-temperature quantum quasinormal mode (QNM) theory for cavity magnonic systems containing non-reciprocal magnetic media, material dissipation, open-cavity radiation losses and thermal fluctuations. It uses macroscopic quantum electrodynamics and complex coordinate transformations to quantize the QNMs. The authors apply the theory to hybrid dielectric-magnonic resonators coupled to spin and superconducting qubits, showing modal interference, a transition from coherent to dissipative coupling, and magnon-mediated qubit synchronization.

Suppressing microwave crosstalk in superconducting quantum processors by designing parasitic capacitances

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Suppressing microwave crosstalk in superconducting quantum processors by designing parasitic drive capacitances arXiv · Oct 27, 2026This paper studies how unwanted microwave drive crosstalk between qubits in a superconducting quantum processor can be reduced. The authors build a detailed circuit model of a processor with two fixed-frequency transmon qubits and a tunable coupler, and experimentally show that crosstalk can be suppressed. They find the suppression comes not only from cancelling the effective qubit-qubit coupling but also from interference among other coupling paths. The authors conclude that choosing suitable parasitic capacitances can suppress crosstalk, suggesting that parasitic coupling paths should be engineered rather than simply minimized.

Multi-day magnetic imaging of single living cancer cells using a quantum sensor

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Multi-day single-cell magnetic imaging of living cancer cells using Quantum Cell Monitoring arXiv · Oct 27, 2026This paper presents Quantum Cell Monitoring (QCM), a widefield nitrogen-vacancy magnetometry platform that records single-cell information from stray magnetic fields instead of emitted photons, at subcellular resolution. Combined with a live-cell incubator, it tracks magnetically labeled living cancer cells for up to 72 hours. The authors report observing mitosis, morphological changes, and cluster formation, splitting, and migration.

Upper bounds on how often feedback-controlled quantum trajectories exceed quantum speed limits

2026-10-27T00:00:00+09:00

Probability bounds on trajectory-level exceedances of quantum speed limits under continuous-measurement feedback arXiv · Oct 27, 2026This paper studies the probability that a single conditioned quantum trajectory, under continuous measurement feedback, exceeds a quantum speed limit (QSL) velocity derived from an ensemble. Using the finite-time average fidelity velocity, the authors bound this exceedance probability in terms of its mean and variance, and obtain state-independent bounds, including an exponential concentration bound. For a feedback-controlled qubit they give explicit model-specific bounds that are nontrivial at short times. They also identify a finite-time regime where the exceedance probability is exactly zero because the conditioned dynamics have restricted support. Monte Carlo simulations confirm the analytical bounds and show their tightness.

Preparing Geometric States on the Bloch Sphere with a Linear Mechanical Resonator

2026-10-27T00:00:00+09:00

Experimental Geometric State Preparation on the Bloch Sphere Via Linear Mechanical Resonator arXiv · Oct 27, 2026This paper applies the Bloch sphere representation, familiar from quantum two-level systems, to a linear two-mass, three-spring mechanical system. The system is driven from both ends at a fixed frequency between its two resonances, producing tunable superpositions of its symmetric and antisymmetric modes. Laser vibrometer measurements and frequency-domain analysis are used to extract the modal coefficients and map them onto Bloch sphere coordinates. The results show planar rotations under phase sweeps and continuous steering between eigenstates under amplitude-ratio tuning.

Quantum fluid dynamics built on Nambu's unpublished fluid notes

2026-10-27T00:00:00+09:00

Quantum hydrodynamics from Nambu's unpublished fluid notes arXiv · Oct 27, 2026This paper develops a quantum hydrodynamic theory based on an unpublished note by Nambu on fluid dynamics. Tracing out unobserved fluid modes yields a quantum channel for an observed cyclic deformation, and a criterion is given for exact preservation of coherence between opposite momenta. Using two shear flows as an example, the authors identify an exact noiseless sign subsystem and show that a preparation with smaller initial decoherence can still suffer larger maximum loss over a finite readout interval.

Quantum computing study of bulk FeO ground-state properties

2026-10-27T00:00:00+09:00

Towards Quantum Computation of Bulk FeO arXiv · Oct 27, 2026This paper studies the ground-state properties of molecular FeO and Fe2O2 model Hamiltonians using classical exact diagonalization, the Variational Quantum Eigensolver (VQE), and Sample-based Quantum Diagonalization (SQD). The experimentally known quintet ground state of FeO is recovered both classically and with quantum algorithms, and a nonet ground state is found for Fe2O2. Raw VQE does not reach chemical accuracy, but SQD with two connectivity shells recovers the exact ground energy for both molecules using very few quantum resources.

Semiconductor quantum dot produces quantum light with adjustable Wigner negativity

2026-10-27T00:00:00+09:00

Generation of quantum light with tunable Wigner negativity with a semiconductor quantum dot arXiv · Oct 27, 2026This study uses a single semiconductor quantum dot inside a cavity to generate quantum light states with tunable Wigner negativity. Optical coherent control of the dot's transition creates a superposition of zero and one photon, which is characterized point by point in phase space via homodyne measurement. Wigner-function negativity appears as excitation power increases. After correcting for collection and propagation losses, fidelities to the ideal state and quantum purities exceed 95%.

Ultrafast light-electron modulation for free-electron quantum optics

2026-10-27T00:00:00+09:00

Ultrafast light-electron modulation for free-electron quantum optics: fundamentals and applications arXiv · Oct 27, 2026This paper proposes a unified Light-Electron Modulation (LEM) framework that treats optical near fields as programmable phase modulators for free-electron wavepackets. It identifies longitudinal energy and transverse momentum modulation channels and describes how their operation depends on wavepacket extent, recoil, phase matching, and field geometry. The authors show that PINEM, Raman-Nath and Bragg diffraction, DLA-like acceleration, and anomalous PINEM can be organized as limiting regimes of one modulation picture, and they derive design principles for free-electron modulators.

Optical tensor processing for simulating quantum circuits

2026-10-27T00:00:00+09:00

Quantum circuit simulation with high-order optical tensor processing arXiv · Oct 27, 2026This paper presents a classical optical architecture for quantum circuit simulation that treats gates and input-state batches as independent tensor dimensions and maps eligible tensor network contractions onto the same processor. Using multidimensional encoding and readout across spatial and wavelength degrees of freedom, the authors experimentally realize high-order tensor-matrix multiplication in a single propagation for all computational-basis inputs of a 4-qubit gate. A physics-based optical propagation model is used to numerically evaluate the approach for the Deutsch algorithm and a tensor network covering all 128 target instances of a 7-qubit Grover algorithm.

Analog quantum experiments with automatic differentiation: from programs to atoms

2026-10-27T00:00:00+09:00

Analog Quantum Experiments Meet Automatic Differentiation - from Programs to Atoms arXiv · Oct 27, 2026This paper introduces DiffSimuQ, a method that applies automatic differentiation to a broad class of open-loop analog quantum experiments. It transforms an experiment program into a derivative program whose expected outcome equals the gradient. For continuous evolution it gives two realizations, the Nyquist shift rule for general time-dependent evolution and a parameter-shift realization for involutory generators. In noisy emulation, both avoid the finite-difference error floor and improve closed-loop optimization.

Estimating entanglement in many-body states from partial-transpose moments

2026-10-27T00:00:00+09:00

Many-body entanglement quantification in arbitrary states through a few partial-transpose moments arXiv · Oct 27, 2026This paper shows how the logarithmic negativity, a measure of entanglement, can be estimated for an arbitrary many-body state without reconstructing the state. It uses a finite number of even partial transpose moments and solves a truncated Hausdorff moment problem with Gauss and Gauss-Radau quadrature. The resulting lower bounds improve as the moment order increases and are illustrated on ground states of three interacting spin models and a thermal state, with an error analysis for finite statistics. ★★★★ Notable: Using finitely many even partial-transpose moments and a truncated Hausdorff moment problem, the authors derive progressively tightening lower bounds on logarithmic negativity, illustrated on spin-mod

Non-Hermitian Schwinger effect in imaginary magnetic fields

2026-10-27T00:00:00+09:00

Non-Hermitian Schwinger effect in an imaginary magnetic field arXiv · Oct 27, 2026The authors analyze the one-loop effective Lagrangian of scalar and Dirac QED in a real electric field combined with a parallel imaginary magnetic field. They show that the imaginary magnetic field adds an extra pole family to the proper-time integrand and can produce a nonzero imaginary part even without an electric field. When the field-strength ratio is rational, some poles coincide and require careful treatment.

Algebraic characterisation of invariants for n-qubit pure states

2026-10-27T00:00:00+09:00

An algebraic characterisation of n-qubit pure-state invariants arXiv · Oct 27, 2026This paper studies n-qubit pure quantum states written as density matrices in Bloch representation. The authors define a family of quadratic functions of Pauli expectation values and fully determine which choices yield state-independent purity constraints. The resulting invariants are closely tied to the geometry of symplectic polar spaces. A subfamily stable under state updates is shown to correspond to symplectic Lie algebras generated by Pauli operators.

Training quantum circuits by learning from equilibrium states of a physical model

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Equilibrium Learning of Quantum Circuits arXiv · Oct 27, 2026This paper extends equilibrium learning, which trains physical systems using observables of their relaxed states, to gate-based quantum circuits. A parametrized circuit is embedded in a Feynman-Kitaev Hamiltonian, and the compilation target is imposed via an output clamping term or a target-dependent cyclic condition on the clock register. Cost functions for unitary and state compilation are defined using ground state energies and overlaps with the free history state. In two-qubit benchmarks, optimization with these equilibrium costs reaches a fixed fidelity threshold in fewer sweeps than the standard compilation infidelity cost for many instances.

Diagonal, Switching, and Locally Optimal Unraveling: an efficient method for quantum trajectories in metastable open systems

2026-10-27T00:00:00+09:00

Diagonal, Switching, and Locally Optimal Unraveling for efficient quantum trajectories in metastable open quantum systems arXiv · Oct 27, 2026This paper introduces DiSLOU, a method for efficiently simulating quantum trajectories in open quantum systems that exhibit metastability. It combines three optimization layers: switching among locally optimal unravelings that minimize quantum jumps, diagonalizing the non-Hermitian effective Hamiltonian once per attractor to speed up no-jump evolution, and propagating states in a truncated subspace of slowly decaying eigenmodes. The method is tested on a driven-dissipative Kerr resonator, with the largest speedup in the bistable regime, and applied to rare bit-flip events in the cat manifold of a dissipatively stabilized parametric oscillator, where it gives over an order of magnitude improvement.

Interactions between spin-like states in ultracold molecules, a step toward precision tests of physics

2026-10-27T00:00:00+09:00

Parity-doublet spin interactions in ultracold polyatomic molecules arXiv · Oct 27, 2026This paper reports observing and controlling resonant dipolar exchange interactions between parity-doublet states in ultracold polyatomic CaOH molecules held in an optical trap. The researchers encode a pseudospin in these states and detect density-dependent loss of Ramsey contrast and a mean-field precession whose sign reverses with the initial population imbalance. Floquet engineering of the interaction anisotropy suppresses many-body dephasing near the SU(2)-symmetric Heisenberg point. ★★★★ Notable: The authors report the first observation and control of resonant dipolar exchange in parity doublets of ultracold CaOH molecules, state that one discrete truncated Wigner model describes both the Rams

Scaling Laws for Conditional Mutual Information in Random Classical Systems

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Universal Scaling of Conditional Mutual Information in Classical Stochastic Dynamics arXiv · Oct 27, 2026This paper studies how conditional mutual information (CMI), which measures dependence between two regions given an intervening buffer, evolves in one-dimensional classical stochastic models. The authors propose a universal scaling form for systems whose Markov length grows with time and derive it in the inactive phase of parity-conserving directed percolation. A Hankel-based truncation scheme enables matrix-product-state simulations that verify the scaling. The CMI between fixed microscopic regions is found to share a common scaling dimension of two.

Mesons, Confinement, and Krylov Complexity in a Long-Range Ising Chain

2026-10-27T00:00:00+09:00

Mesons, Confinement, and Complexity: A Krylov Space Perspective on the Long-Range Ising Chain arXiv · Oct 27, 2026This paper studies how confinement and Krylov complexity are linked in a long-range transverse-field Ising chain, where power-law interactions create an effective confining potential between domain walls. Using the time-averaged Krylov state complexity after a quench as a diagnostic, the complexity is strongly suppressed at small α and small transverse field, and grows rapidly at larger α. In the confined regime, the oscillation frequencies match the meson masses of an effective two-kink model.

Typical entanglement growth and transport fluctuations in a quantum exclusion model

2026-10-27T00:00:00+09:00

Typicality of entanglement growth and transport fluctuations in quantum symmetric exclusion processes arXiv · Oct 27, 2026This paper studies the quantum symmetric exclusion process, a model of randomly hopping free fermions with diffusive transport and long-range quantum coherence, using macroscopic fluctuation theory. The authors show that charge-transfer statistics for individual noise realizations almost surely match those of the classical symmetric exclusion process at long times, both in equilibrium and after quenches from diagonal product states. They also derive asymptotically exact predictions for entanglement growth from domain-wall and Néel initial states, which agree well with numerical simulations.

Symmetry-resolved fermionic correlations in iron-oxide ground spaces

2026-10-27T00:00:00+09:00

Symmetry-resolved fermionic correlations in iron-oxide ground spaces arXiv · Oct 27, 2026This paper studies how symmetries organize degenerate ground states in many-body electronic models of FeO and Fe2O2. Resolving the same degenerate ground space with different symmetry operators yields states with very different correlation properties. With density-density Hund interactions added, the FeO ground space reduces to a spin-reversal pair with maximal magnetization.

An open effective field theory for dark matter searches with matter-wave interferometers

2026-10-27T00:00:00+09:00

An open EFT for dark matter searches with matter-wave interferometers arXiv · Oct 27, 2026This paper treats matter-wave interferometers as open quantum systems coupled to a dark matter environment and derives an open effective field theory using the Schwinger-Keldysh formalism. The framework describes two signatures, dark matter-induced phase shifts and loss of contrast. The authors analyze elastic spin-independent sub-GeV dark matter scattering off nucleons and discuss the regions of parameter space that composite-particle interferometers could probe for Higgs-portal and light hadrophilic scalar mediated dark matter.

An analytic bootstrap method for solving quantum mechanics of a particle on a circle

2026-10-27T00:00:00+09:00

Analytic Bootstrap Solution for Quantum Mechanics on a Circle arXiv · Oct 27, 2026The paper solves the Schrödinger equation for a particle on a circle using a quantum mechanical bootstrap approach. It requires the solutions of recursion relations for Fourier coefficients to vanish exponentially fast, yielding a generalized continued fraction representation that is analytic in the couplings and energy. The authors show how to compute the density of states, reconstruct the wave function, and extract quasimomentum versus energy. Applied to the Mathieu equation, the method resolves exponentially small bands in the spectrum.

AlgebrasTQD: A Tool for Computing Algebras and Interfaces in Twisted Quantum Doubles

2026-10-27T00:00:00+09:00

AlgebrasTQD: Computing Algebras and Interfaces in Twisted Quantum Doubles arXiv · Oct 27, 2026This paper presents AlgebrasTQD, an open-source GAP program for computing condensable algebras and their topological boundaries and interfaces in twisted quantum doubles. It can classify 1+1d gapped and gapless phases related to a finite group by gauging, study 2+1d anyon proliferation, and construct logical gates in non-Abelian topological codes. The paper illustrates its use with several Abelian and non-Abelian groups and states that all arithmetic is exact.

A paper linking qubit- and boson-based quantum sensing methods for detecting new physics

2026-10-27T00:00:00+09:00

A Correspondence Between Qubit- and Boson-Based Sensing Protocols arXiv · Oct 27, 2026The paper uses the Holstein–Primakoff transformation to unify qubit-based and boson-based sensing proposals within one framework. It introduces a novel generalization of GHZ states that performs better at detecting rare interactions, and states these states can be readily prepared while combining GHZ coherence with improved error rejection. It also extends the Hamiltonian-Not-in-Lindblad-Span theorem to collections of bosonic modes.

How amorphization depth affects bismuth redistribution and activation in silicon for quantum devices

2026-10-26T00:00:00+09:00

Amorphization-Depth-Dependent Bismuth Redistribution and Activation in Silicon for Quantum Devices arXiv · Oct 26, 2026The study compares 20 keV bismuth implantation directly into silicon with implantation after silicon preamorphization. The two routes produce amorphous layers of about 47 nm and 177 ± 15 nm deep. After annealing at 650 °C for 300 s, substitutional Bi fractions are similar (91 ± 2% and 89 ± 4%), but Hall-derived electrical activation is about 60% and 90%. The results show that amorphization depth and regrowth geometry govern Bi redistribution and affect electrical activation beyond substitutional incorporation alone.

A solvable obstructed seam on a lattice Klein bottle, and how register choice affects toric codes

2026-10-20T00:00:00+09:00

An exactly solvable obstructed seam on a lattice Klein bottle: bulk-locked Majorana rings and register-dependent toric codes arXiv · Oct 20, 2026The paper studies a frustrated seam formed by reflection-gluing Wen's plaquette model on a closed lattice Klein bottle. Its seam operators reduce to free Majorana rings, and bulk stabilizers restrict the allowed sectors, yielding exact ground energies, gaps and degeneracies. It contrasts this with consistent toric-code realizations using an edge register, which preserves anyon labels, and a Hadamard-dressed site register, which has colour-dependent seam transport.

Quantum circuits for elastic wave equations using Schrödingerisation

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Quantum circuits of elastic wave equations via Schrödingerisation arXiv · Oct 27, 2026This paper builds explicit quantum circuits for the velocity-stress form of elastic wave equations in homogeneous media, using Schrödingerisation. The equations are rewritten in symmetric matrix form, with Fourier spectral discretization for periodic problems and staggered-grid finite differences for physical boundaries. The authors analyze splitting errors and CNOT-gate counts for higher-order Trotter-Suzuki formulas and compare with classical partitioned splitting, finding a polynomial improvement in spatial-resolution dependence. Noiseless circuit simulations illustrate the constructions and quantify errors against exact and classical reference solutions.

Matrix samplers and quantum-proof extractors: equivalence and near-optimal constructions

2026-10-27T00:00:00+09:00

Matrix Samplers and Quantum-Proof Extractors: Their Correspondence and Almost-Optimal Constructions arXiv · Oct 27, 2026The paper establishes an equivalence between matrix samplers and quantum-proof randomness extractors, extending Zuckerman's classical sampler-extractor correspondence. Using this equivalence, the authors construct explicit strong matrix samplers with optimal randomness overhead and near-optimal sample complexity. They also obtain strong quantum-proof extractors with improved seed and output lengths. ★★★★ Notable: The authors show matrix samplers and quantum-proof extractors are equivalent, and use this to build explicit strong matrix samplers with fewer samples and shorter seeds than prior work.

Quantum evolution kernel for embedding attributed graphs on neutral-atom computers

2026-10-27T00:00:00+09:00

Quantum Evolution Kernel for Node-Attributed Graphs arXiv · Oct 27, 2026This paper proposes a way to embed node-attributed graphs on neutral-atom quantum computers and applies it to digit recognition. It extends PASQAL's quantum evolution kernel with a node-level encoding based on three-level quantum states, and uses the resulting correlation-based information for classification. The quantum process is simulated with the Pulser library, which limits dataset size. On digit recognition, the method using the Wasserstein distance achieves higher mean accuracy than commonly used Jensen-Shannon distance-based methods.

Circuit-aware mutation testing for quantum programs: exact visibility and execution planning

2026-10-27T00:00:00+09:00

Toward Circuit-Aware Mutation Testing for Quantum Programs: Exact Visibility and Execution Planning arXiv · Oct 27, 2026This paper proposes a circuit-aware framework for mutation testing of quantum programs, distinguishing whether surviving mutants leave behavior unchanged, are hidden by input or measurement choices, or lack sufficient statistical evidence. It targets ideal, noiseless programs with mutations that replace one gate or subcircuit, combining mathematical checks with statistical estimates. For supported cases, it gives conditions under which a test cannot reveal a mutation and exact effect formulas, along with a decision procedure, guarantees, and a small-circuit reference implementation.

Lifting Quasi-Cyclic Additive Codes to Certified Quantum Codes

2026-10-27T00:00:00+09:00

Ancestor Lifting of Quasi-Cyclic Additive Codes and Certified Quantum Codes arXiv · Oct 27, 2026This paper studies additive codes over F4 that correspond to binary quantum stabilizer codes, focusing on 1-generator (1,2)-quasi-cyclic additive codes. It gives an ancestor-lifting theorem for composite lengths, dimension laws, and a palindromic criterion for symplectic self-orthogonality. Exact quantum distances are determined through information-set decoding screening, Brouwer–Zimmermann computation, and independent witness verification. The authors certify a set of record-breaking binary quantum codes and report further propagated entries and upper bounds.

Tensor-train method for simulating quantum system dynamics in phase space

2026-10-27T00:00:00+09:00

Dynamical Tensor Train Approximation for Wigner--Fokker--Planck Equation with Applications to Open Quantum Systems arXiv · Oct 27, 2026This paper presents a dynamical tensor-train method for solving the Wigner–Fokker–Planck equation, which describes continuous-variable open quantum systems. The Wigner function is evolved directly in tensor-train form using a projector-splitting integrator, and the nonlocal Wigner pseudo-differential operator is handled with low-rank representations and matrix-free exponential actions. Numerical experiments in one, two, and three spatial dimensions show the method's accuracy and scalability, including simulations in a six-dimensional phase space.

Scaling and renormalization theory applied to grokking in neural networks

2026-10-27T00:00:00+09:00

Scaling and Renormalization in Neural Networks: An Effective Renormalization-Group Description of Grokking arXiv · Oct 27, 2026This paper examines whether scaling and renormalization group theories can describe grokking, the delayed shift from memorization to generalization in deep neural networks. Using a two-layer network trained on modular addition, the authors define an order parameter and fluctuation measures, then apply real-space renormalization with a coupling matrix to derive five critical exponents. The reported direct empirical estimates match the theoretical predictions within 1 to 10 percent, and the authors propose this formalism as a tool for studying neural network dynamics.

The QICK Box: A Modular Hardware System for Controlling and Reading Out Qubits

2026-10-03T00:00:00+09:00

The QICK Box: A Modular RF Front-End System for Quantum Control and Readout arXiv · Oct 3, 2026The summary in this language did not pass the date and amount checks, so it is withheld. Check the original.

Preparing large cat states efficiently with optical operations

2026-09-30T00:00:00+09:00

Generation of large-amplitude squeezed cat states with near-unity efficiency arXiv · Sep 30, 2026The paper proposes an all-optical scheme that uses quantum non-demolition interactions and photon-number measurements to prepare large-amplitude cat states with near-unity probability. No particular photon-number outcome is postselected; every outcome adds to the accumulated photon number, and the protocol repeats until a required threshold is reached. The authors show the scheme is robust to realistic photon loss, the dominant error source in optical systems.

Optical realization of a cavity field with uniformly moving mirrors

2026-10-11T00:00:00+09:00

Photonic realization of an electromagnetic cavity field with uniform mirror motion arXiv · Oct 11, 2026This paper mathematically studies the effective Hamiltonian of a non-stationary electromagnetic cavity field with uniform linear mirror motion, introduced by C. K. Law. The authors reinterpret bosonic coupling terms as generators of the symplectic algebra Sp(4,R), which can be implemented with linear optical elements, allowing strong effective interactions. They derive analytical expressions for the average photon number in each mode and show generation of two-mode squeezed states. Statistical properties such as intermode correlations, the Mandel parameter, and linear entropy are analyzed, and the Wigner function visualizes the system's behavior in phase space.

Comparing zero- and infinite-temperature damping in variational quantum circuits, covering feature scale, sampling cost, and frame gauge

2026-10-01T00:00:00+09:00

Zero- Versus Infinite-Temperature Damping in Variational Quantum Circuits: Feature Scale, Sampling Cost, and Frame Gauge arXiv · Oct 1, 2026This paper compares amplitude damping with its Pauli-twirled version, which is generalized amplitude damping at infinite temperature, to isolate the effect of zero-temperature bias in variational quantum circuits. The bias acts mainly through feature scale, and features shrink under both damping models. A trainable output scale removes most accuracy differences, but the cost reappears as additional measurement shots.

Localising logical information in stabiliser codes using single-qubit measurements

2026-10-01T00:00:00+09:00

Logical information localisation in stabiliser codes via single-qubit measurements arXiv · Oct 1, 2026This paper studies stabiliser path finding (SPF), a method for concentrating logical information from a stabiliser code with lost qubits onto a target qubit using one round of single-qubit measurements. It introduces g-SPF, which localises information onto at most g unspecified target qubits, and proves that for i.i.d. loss probability p<1/2 and large planar surface codes, this succeeds with probability tending to one, establishing a localisation threshold. The authors also present an exact integer linear programming algorithm and a faster heuristic decoding-based algorithm, validated on the surface code.

Universal Inductive Inference of Quantum States: a framework for learning and predicting quantum sources from measurement data

2026-09-29T00:00:00+09:00

Universal Inductive Inference of Quantum States arXiv · Sep 29, 2026The paper extends Solomonoff's universal inductive inference to quantum systems, introducing a framework for learning and predicting quantum sources that may have arbitrary correlations and entanglement across time. Given past measurement outcomes and post-measurement systems, the learner outputs a joint state predicting the next outcome while preserving correlations with past systems. The authors give an information-theoretic inference algorithm with round complexity O(sε⁻²δ⁻¹), prove a matching lower bound in the relevant regime, and construct a non-i.i.d. state tomography algorithm. They also investigate computational hardness under quantum cryptographic assumptions. ★★★★ Notable: Extends Solomonoff universal induction to quantum sources with arbitrary cross-time correlations and entanglement, giving an inference algorithm with round complexity O(sε^-2δ^-1) and reporting a matc

Universal quantum coding using Schur-Weyl duality for error correction without prior channel knowledge

2026-09-30T00:00:00+09:00

Universal quantum coding arXiv · Sep 30, 2026This paper addresses entanglement distillation from unknown noisy bipartite states and reliable quantum communication over noisy channels without prior knowledge of the state or channel. Using Schur-Weyl duality, the authors treat the irreducible permutation spaces from multiple copies of an unknown mixed state as maximally entangled code spaces and correct their symmetry-resolved errors. The work unifies entanglement distillation, quantum error correction and quantum communication within one representation-theoretic framework, with finite-copy guarantees. ★★★★★ Notable: The authors use Schur-Weyl duality to build universal quantum codes needing no prior knowledge of the state or channel, unifying entanglement distillation and communication with claimed worst-case opt

Transverse momentum as the counter-diabatic generator in bent waveguide couplers

2026-09-29T00:00:00+09:00

Transverse momentum as the counter-diabatic generator in bent waveguide couplers arXiv · Sep 29, 2026This paper studies bent mode-evolution couplers, where bending the waveguide axis suppresses coupling between supermodes. The authors identify transverse momentum as the operator that generates the required counter-diabatic term. They derive a closed-form expression for the axis slope and compare the design with a straight coupler using a unitary transformation, reporting supermode fidelities of 0.994 and 1.000.

A rigidity theorem: Gaussian states dominating separable operators are separable

2026-09-29T00:00:00+09:00

Separability rigidity of Gaussian states under positive domination arXiv · Sep 29, 2026The paper proves that a finite-mode Gaussian state is separable across a fixed mode partition if it dominates a nonzero positive operator that is separable across that partition. Three consequences follow: a Gaussian channel with a nonzero entanglement-breaking subchannel is entanglement breaking, and a connected graph of entangled two-mode Gaussian marginals certifies genuine multipartite entanglement. The authors also show full inseparability and genuine multipartite entanglement coincide for finite-mode Gaussian states. ★★★★ Notable: The authors prove a separability rigidity theorem for finite-mode Gaussian states: if a Gaussian state dominates a nonzero positive operator separable across a fixed partition, the state itself is sep

Placement-driven reversal of preferred spin alignment in monolayer hBN vacancy pairs

2026-09-28T00:00:00+09:00

Placement-driven reversal of preferred spin alignment in monolayer hBN vacancy pairs arXiv · Sep 28, 2026This paper studies how two negatively charged boron vacancies in monolayer hexagonal boron nitride align their spins when they interact. Using density-functional theory across seven configurations, the authors find that moving one vacancy by a single lattice vector reverses the preferred collinear spin alignment. The closest pair, 4.3 angstrom apart, favours parallel alignment, while a 7.5 angstrom pair favours antiparallel alignment.

Quantum Networking at Quantum Computing Speed: Kilohertz Entanglement Between Different Quantum Systems

2026-10-08T00:00:00+09:00

Quantum Networking at the Speed of Quantum Computation: Kilohertz Entanglement in a Heterogeneous Quantum System arXiv · Oct 8, 2026The paper entangles a trapped barium ion with a silicon-vacancy center in a diamond nanophotonic cavity. A photon from the ion is converted in wavelength and encoding, reflected off the cavity system, and detected, and one detected photon signals successful entanglement. Including all conversion losses, the average generation rate is 1.03 kHz, about one Bell pair per millisecond, matching the cycle time of planned trapped-ion processors. ★★★★ Notable: Entangles a trapped ion with a diamond SiV center at about 1 kHz, four times faster than prior ion-ion photonic links, shown experimentally.

Equivalence of topological indices for U(1)⋊Z₂-symmetric quantum spin chains

2026-09-28T00:00:00+09:00

The equivalence of topological indices for U(1)rtimesℤ₂-symmetric quantum spin chains arXiv · Sep 28, 2026This paper studies symmetry-protected topological phases in integer-spin quantum chains with on-site U(1)⋊Z₂ symmetry. It proves that Ogata's operator-algebraic index and Tasaki's elementary twist index are equivalent, giving an explicit error bound for computing the index. Combined with a boundary-field gap theorem and earlier calculations, it shows that the infinite S=1 antiferromagnetic Heisenberg chain has a symmetric gapped ground state with both indices equal to −1. ★★★★ Notable: The authors prove equivalence of Ogata's and Tasaki's twist indices for U(1)⋊Z2 integer-spin chains with explicit error bound, and report both indices equal -1 for the infinite S=1 Heisenberg chain.

Magnetic localization and spectral asymmetry of a charged particle near a screw dislocation

2026-09-27T00:00:00+09:00

Magnetic localization and spectral asymmetry of a charged particle at a screw dislocation arXiv · Sep 27, 2026The paper studies a charged particle moving outside a screw dislocation in a uniform magnetic field. Although the geometry is locally Euclidean, the global screw identification couples conserved axial and azimuthal quantities. After separating cyclic coordinates, radial motion is governed by an inverse-square term and a magnetic harmonic confining term. For nonzero field strength the reduced problem is exactly solvable, giving an equally spaced spectrum with an orientation-dependent energy shift.

Charging quantum batteries in a balanced loss-gain cavity pair

2026-10-06T00:00:00+09:00

Charging Dicke and Tavis--Cummings quantum batteries with a PT-symmetric lossy--gain cavity pair arXiv · Oct 6, 2026This paper studies how a parity-time-symmetric photonic environment affects charging of Dicke and Tavis-Cummings quantum batteries. Each cavity holds an identical battery to keep the symmetry intact. In the broken phase the gain-side battery stores more energy, while in the unbroken phase it stores less than the lossy-side battery. The optimum lies on the broken side, near but not at the exceptional point.

Minimal output entropy for box-adding or removing Young diagram channels, and a general Pauli principle

2026-09-27T00:00:00+09:00

Minimal output entropy for the channels that add or remove a box of a Young diagram, and a Pauli principle for every permutation symmetry arXiv · Sep 27, 2026The paper studies four covariant quantum channels connecting irreducible U(d) representations whose Young diagrams differ by one box. The authors prove that for each channel, coherent states produce outputs that majorize all others, so coherent states minimize output entropy, and they give the optimal output explicitly using hook lengths. For the two channels that keep the box, they also identify all minimizers, which need not be coherent even when pure. Applied to N particles with a given permutation symmetry, the results give sharp bounds on the spectrum of a single particle's reduced density matrix and characterize the spectra reachable by mixed states; for fermions these recover the Pauli principle and Coleman's theorem.

Exact Trotter error analysis for the degenerate quantum Rabi model

2026-09-29T00:00:00+09:00

Exact Trotterization in the Degenerate Quantum Rabi Model arXiv · Sep 29, 2026This paper studies digital quantum simulation of the quantum Rabi model in the deep strong coupling regime, where Trotterization errors were previously known only through qualitative bounds. In the exactly solvable degenerate limit, the authors show that the first-order Trotter operator has a closed form and that the generated phase-space trajectory lies exactly on a rescaled, rotated circle. This yields a closed-form expression for state fidelity. They also report that promoting the Trotter-step coupling to a complex amplitude corrects this geometric error without additional circuit cost.

Improved quantum algorithms for decomposing black-box Abelian groups into cyclic factors

2026-09-29T00:00:00+09:00

Improved Quantum Algorithms for Black-Box Abelian Group Decomposition arXiv · Sep 29, 2026This paper presents a quantum algorithm that decomposes finite Abelian black-box groups into cyclic factors. It adapts quantum sampling and classical lattice reduction from Regev's factoring algorithm to compute an invariant-factor decomposition with high probability. Compared with the Cheung-Mosca approach, the authors report lower total gate counts, quantum time bounds, and qubit requirements.

Collectivity: a mechanism that limits quantum entanglement even with long-range interactions

2026-09-29T00:00:00+09:00

Collectivity limits quantum entanglement arXiv · Sep 29, 2026This paper studies how ground-state quantum entanglement is limited in gapped many-body systems with long-range power-law interactions. The authors show that many weak interactions produce fluctuations controlled by their square-summed strength, a mechanism they call collectivity. They derive logarithmic or subextensive entanglement bounds for arbitrary bipartitions and polylogarithmic bounds for regular bipartitions, and show several of these scalings are optimal. ★★★★★ Notable: The authors show collectivity, not locality, limits entanglement under power-law interactions, reporting entanglement bounds and optimality results for long-range many-body systems.

Observation of a topological defect state in the quantum Rabi model

2026-09-28T00:00:00+09:00

Observation of a topological defect state in the quantum Rabi model arXiv · Sep 28, 2026This paper realizes a topological defect state of the quantum Rabi model, a spin coupled to an oscillator, using a single trapped 171Yb+ ion. Reconstructed phase-space distributions show centroid trajectories with windings of one and zero in two regimes as the coupling phase varies, linking discrete-lattice topology to the oscillator's continuous phase space. Measured spin responses to drive-amplitude modulation relate the stability of spin polarization to energy gaps and allowed transitions.

A spectral threshold guaranteeing non-maximal Schmidt number

2026-09-28T00:00:00+09:00

A threshold for maximal Schmidt number from spectrum arXiv · Sep 28, 2026The paper asks when the eigenvalue spectrum of a bipartite state on C^d⊗C^d alone ensures its Schmidt number is not maximal. Using spectral bounds for (d-1)-block positive operators, it proves that states whose largest eigenvalue does not exceed the sum of their p smallest eigenvalues, for p ≤ ⌊d²/2⌋, have Schmidt number at most d-1 under all global unitaries. It also shows that states satisfying the reduction criterion under arbitrary global unitaries belong to this class, while for d ≥ 3 it constructs maximal-Schmidt-number states satisfying the reduction criterion on both subsystems, showing the global unitary requirement is essential.

Quantum data processing equality: a paper turning the quantum data processing inequality into an exact equality

2026-09-28T00:00:00+09:00

Quantum data processing equality arXiv · Sep 28, 2026The paper promotes the quantum data processing inequality, which states that quantum relative entropy does not increase under quantum channels, to an exact equality using boundary and surface Poisson integral representations across a complex strip. The relative-entropy loss splits into two nonnegative components: a Petz recovery term governing state reconstructibility and a boundary term measuring mismatch of relative modular dynamics. The authors also establish recovery bounds at any prescribed modular parameter, with optimal square-root scaling in the relative entropy loss. ★★★★ Notable: Promotes the quantum data processing inequality to an exact equality via Poisson integral representations, decomposing the relative-entropy loss into Petz recovery and boundary terms.

Discrete scale invariance in Ising mesons: how kink motion in a magnet gives log-periodic energy levels

2026-09-29T00:00:00+09:00

Discrete Scale Invariance of Ising Mesons arXiv · Sep 29, 2026The paper studies composite excitations in a transverse-field Ising chain with long-range bonds decaying as 1/r^4. The authors show that dressed domain walls experience an asymptotic inverse-square attraction whose strength is set by spontaneous magnetization. The curvature of the dressed two-kink threshold sets the kinetic scale, and together these determine the scale-anomaly exponent and the meson hierarchy. Full-spin exact diagonalization and a fourth-order weak-field Hamiltonian are reported to support the coupled energy-size scaling in a finite window.

Quantum codes with separate recovery locality for bit-flip and phase-flip errors

2026-09-28T00:00:00+09:00

Asymmetric Entanglement-Assisted Quantum Locally Recoverable Codes arXiv · Sep 28, 2026The paper introduces entanglement-assisted quantum locally recoverable codes with asymmetric locality, where bit-flip and phase-flip errors are corrected from recovery sets of different sizes. It extends a stabilizer-based sufficient condition and, in the CSS framework, places separate locality conditions on the two underlying classical codes. The authors derive Singleton-, Griesmer-, Plotkin-, sphere-packing-, and Cadambe–Mazumdar-type bounds for these codes. They also characterize when a pure CSS-type code built from two classical LRCs meets the Singleton-like bound with equality.

Rényi channel capacity does not rise with non-signaling assistance

2026-09-28T00:00:00+09:00

Monotonicity of the Rényi channel capacity under non-signaling assisted channel simulation arXiv · Sep 28, 2026The paper gives an alternative variational proof that shared non-signaling correlations between sender and receiver cannot increase the Rényi capacity of a classical channel. The result follows from a channel-divergence data-processing inequality by Oufkir, Yao and Berta, and uses a Legendre transform to write capacity as an extremum over affine functionals. Combined with separate arguments for Shannon capacity and endpoint orders, it establishes monotonicity for all orders. The authors also derive consequences for random-coding, sphere-packing and strong-converse exponents.

Optimal Query Complexity for Preparing Ground States

2026-09-29T00:00:00+09:00

Optimal Query Complexity for Ground-State Preparation arXiv · Sep 29, 2026This paper determines the optimal number of queries needed to prepare a quantum system's ground state to trace-distance error ε, given a known energy threshold in the spectral gap. It presents two algorithms, one with expected query count O((α/Δ)(γ⁻¹+log(1/ε))) and another with worst-case count O((α/(γΔ))log(1/ε)). A lower bound matching the expected query count is also proven. ★★★★★ Notable: The authors report matching upper and lower bounds on ground-state preparation query complexity under a known energy threshold, with expected and worst-case query counts from spectral-filter purificat

Estimating teleportation costs for distributed quantum chemistry circuits

2026-09-29T00:00:00+09:00

Quantifying Teleportation Overhead in Distributed Unitary Coupled-Cluster Ansätze arXiv · Sep 29, 2026This paper estimates the resources needed to run unitary coupled-cluster circuits for hydrogen chains across distributed quantum processors using teleportation. It compares a naive distribution method with the TeleSABRE algorithm, counting Bell pairs and classical communication for nonlocal two-qubit gates. The authors find that UpCCD with spin-blocked Jordan-Wigner ordering scales most favorably, while UCCSD requires substantially more distributed resources.

Two-copy measurements close the single-copy gap to the Holevo bound

2026-09-29T00:00:00+09:00

Closing a single-copy gap to the Holevo bound with two-copy measurements arXiv · Sep 29, 2026This paper studies whether the Holevo Cramér-Rao bound for quantum multiparameter estimation can be attained with finite copies of a state. The authors construct a three-parameter rank-two model whose Holevo bound cannot be reached with one copy but is attained exactly with two, and they prove that full-rank models retain a finite-copy gap for any number of parameters. They also experimentally implement the two-copy collective measurement on superconducting qubits, observing error below single-copy and separate-measurement bounds, with this advantage persisting over a finite range of depolarizing noise. ★★★★ Notable: The authors construct a three-parameter rank-two model where one copy cannot reach the Holevo bound but two copies do, and give a proof of finite-copy gap persistence for full-rank models, disproving

Measurement-feedback interval can induce order in quantum Boltzmann samplers

2026-09-29T00:00:00+09:00

Ordering controlled by the measurement-feedback interval in quantum Boltzmann samplers arXiv · Sep 29, 2026This paper studies whether changing only the measurement-feedback interval, with fixed couplings and a fixed local dissipative rule, can induce ordering in a quantum Boltzmann sampler. At zero environmental dephasing, repeated projective measurements remove transverse coherence regenerated during relaxation, enhancing the local longitudinal response. In the Curie–Weiss limit, for couplings below the equilibrium threshold, shortening the readout interval drives a continuous transition to an ordered stationary state even though the programmed Boltzmann distribution remains disordered.

Quantum States and Spectra of Small Cylindrical and Toroidal Lattices

2026-09-29T00:00:00+09:00

Quantum States and Spectra of Small Cylindrical and Toroidal Lattices arXiv · Sep 29, 2026This paper studies the spectra and quantum states of small cylindrical and toroidal lattices under a scalar gauge potential that adds a position-dependent phase to inter-site coupling. Periodic boundary conditions generally break the gauge equivalence assumed for infinite lattices, and the authors identify conditions that restore it. They report gauge-dependent avoided crossings and persistent degeneracies, and examine the effects of boundary conditions, coupling strengths, and an axial field.

Block-wise quantum algorithm for PDEs with interface penalties

2026-09-29T00:00:00+09:00

Block-Wise Variational Quantum Algorithms for PDEs with Interface Penalty Constraints arXiv · Sep 29, 2026This paper proposes a block-wise variational quantum algorithm for solving partial differential equations whose solutions vary in complexity across space. The domain is split into local quantum subproblems, with grid sizes and circuit designs assigned according to a computable difficulty indicator. Neighboring blocks are coupled through jump penalties on state values, derivatives, and fluxes, and the rough regions are adaptively tracked. Simulations on elliptic, advection-diffusion, and Burgers problems show lower errors and smaller peak local circuit width than global variational quantum approaches.

Quantum-Selected Configuration Interaction for Benzene Dimer Stacking Energies

2026-09-29T00:00:00+09:00

A Divide-and-Conquer Quantum-Selected Configuration Interaction for Evaluating π-π Stacking Interaction Energies in the Benzene Dimer arXiv · Sep 29, 2026This paper proposes Divide-and-Conquer Quantum-Selected Configuration Interaction (Deep QSCI) to evaluate π-π stacking interaction energies in the sandwich benzene dimer. QSCI is run on one monomer, and a reduced local basis built from its ground state is used to diagonalize an effective dimer Hamiltonian, reusing monomer results across monomers and distances to cut the required qubits from 40 to 20. With 6-31G**, the minimum is -0.91 kcal/mol at 4.0 Å, compared with -1.14 kcal/mol from counterpoise-corrected CCSD(T). With cc-pVDZ, large cancellations appear, which the authors suggest may stem from insufficient consistency of active orbitals and local bases between monomers.

Optimizing randomized quantum simulation of Hamiltonians by minimizing average error

2026-09-29T00:00:00+09:00

Optimized Randomized Hamiltonian Simulation via Average-Error Analysis arXiv · Sep 29, 2026The paper presents a framework for randomized Hamiltonian simulation that samples terms with arbitrary probabilities and implements their short-time evolutions in sequence. It shows that sampling in proportion to Hilbert-Schmidt norms, derived from Haar-averaged error bounds, can give smaller average-error bounds than the standard qDRIFT method. For Pauli-string Hamiltonians, combining this with commuting Pauli grouping further reduces error bounds at fixed depth.

Single-photon nonlinearity from a quantum dot in a nanobeam cavity

2026-09-29T00:00:00+09:00

Single-Photon Nonlinearity from a Nanobeam with a Quantum Dot arXiv · Sep 29, 2026This paper reports a single-photon nonlinearity built from a nanobeam cavity coupled to one quantum dot. The device couples directly to a single-mode fiber with 60% efficiency and reaches the nonlinearity at a threshold of 0.24 incident photons per resonant picosecond pulse. The system operates in the strong-coupling regime, with a coupling rate g/2π of 29.1 GHz and cooperativity C of 3.98. The authors present it as a compact, chip-integrable, fiber-compatible building block for photonic quantum technologies.

Synchronizing quantum devices over lossy channels using polarization assistance

2026-09-29T00:00:00+09:00

Synchronized Quantum Devices in Lossy Channels arXiv · Sep 29, 2026This paper proposes and experimentally demonstrates a polarization-assisted protocol that uses entangled photon pairs to keep quantum devices synchronized under high channel loss, such as satellite-to-ground links. The experiments show reliable synchronization at higher losses and up to a 40% increase in satellite-to-ground distance. Monte Carlo simulations indicate the improvement holds across a wide range of photon-starved conditions.

Root-system structure of sloppiness in passive Gaussian metrology

2026-09-29T00:00:00+09:00

Root-system structure of sloppiness in passive Gaussian metrology arXiv · Sep 29, 2026The paper studies when passive transformations of squeezed Gaussian probes become locally unidentifiable because the quantum Fisher matrix loses rank. It shows that the C_n restricted-root system of Sp(2n,R)/U(n) governs this exact sloppiness for pure zero-mean Gaussian probes. It also solves the E-optimal probe-design problem of maximizing the smallest passive Fisher eigenvalue at fixed mean photon number.

Shared phase arithmetic: applying a layer of diagonal quantum rotations at once

2026-09-29T00:00:00+09:00

Shared Phase Arithmetic for Parallel Quantum Rotations arXiv · Sep 29, 2026The paper proposes parallel phase kickback (PPK), which coherently computes a weighted sum of several rotation parameters, adds it once to a phase-gradient state, and then uncomputes it. This separates the cost of representing a phase function from the cost of applying it. The authors prove correctness, give explicit error bounds, and analyze logical gate counts for general weights, pairs of rotations, and weights with disjoint binary support. The bounds show when shared phase arithmetic reduces amortized rotation cost and when encoding overhead limits that advantage.

A paper on how quantum Fisher information and quantum coherence factorize over time

2026-09-29T00:00:00+09:00

Factorization dynamics between quantum Fisher information and quantum coherence arXiv · Sep 29, 2026This paper studies the factorization relationship between quantum Fisher information, which measures how sensitive a quantum state is to parameter changes, and quantum coherence. The authors prepared pure states in qubit and qutrit systems, applied unitary evolution, and confirmed the factorization law both theoretically and experimentally. They also derived a lower bound on the variance of the estimated parameter that does not require final-state information.

A general spin-chain method for multicomponent anyons in 1D optical lattices

2026-09-29T00:00:00+09:00

Generalized Effective Spin-Chain formalism for multicomponent anyons in one-dimensional optical lattices arXiv · Sep 29, 2026This paper introduces a generalized effective spin-chain (GESC) framework for strongly interacting multicomponent anyons in one-dimensional optical lattices. It maps particle motion to spinless fermions and spin states to an ordered chain, separating spin and charge degrees of freedom. The authors report that in the strong-interaction regime the fractional exchange phase appears in spin-exchange coefficients through virtual tunneling. They also describe how direction-dependent phases affect non-equilibrium impurity transport.

Multicomponent anyons in one-dimensional optical lattices: a study of how particles with fractional exchange statistics behave in a 1D lattice

2026-09-29T00:00:00+09:00

Multicomponent anyons in one-dimensional optical lattices arXiv · Sep 29, 2026This paper studies the ground-state and dynamical behavior of multicomponent interacting anyons confined in a one-dimensional optical lattice, using the Anyon-Hubbard model. It shows that fractional exchange statistics combined with multicomponent effects reshape charge and spin correlations, including asymmetric momentum-distribution shells and new peaks. The authors report antiferromagnetic spin ordering and find that the statistical phase parameter can switch dipole oscillations between underdamped and overdamped regimes.

Emergent symmetries after ensemble averaging: a review of how global symmetries can arise in quantum gravity.

2026-09-29T00:00:00+09:00

Emergent Symmetries in Ensemble Averages arXiv · Sep 29, 2026The paper reviews work showing that global symmetries, believed absent in quantum gravity, can emerge after ensemble averages of theories as encountered in holography. Its case study is the ensemble average of two-dimensional Narain-type conformal field theories with an even quadratic form, computed by the Siegel-Weil formula and interpreted as a sum over geometries in a three-dimensional Abelian Chern-Simons theory. The authors also relate this to the Swampland program and recast strong-to-weak spontaneous symmetry breaking of mixed states as symmetry emergence in ensemble averages, motivating a new Swampland conjecture.

Quantum References Beat Classical Ones for Leakage Detection

2026-09-29T00:00:00+09:00

Exponential Advantage of Quantum over Classical References in Leakage Detection arXiv · Sep 29, 2026The paper shows that leakage from an encoding subspace can be detected using independent quantum reference states prepared by the same encoder, without a classical description of the encoding. For orthogonal leakage, the miss probability is asymptotically 4/M, independent of the ambient dimension. Measuring all references first yields zero detection under the same zero-false-alarm requirement. For one logical qubit in three physical qubits, seven coherent references achieve at least 50% detection, while a measurement-first receiver needs at least 588. ★★★★ Notable: Proposes detecting leakage with independent quantum references from the same encoder, needing no classical encoding description; the authors prove optimality under zero false alarm and report that for

Factorization of driven anisotropic Rabi–Stark Hamiltonians via affine spin pencils

2026-09-29T00:00:00+09:00

Affine spin-pencil factorization of generalized driven anisotropic Rabi--Stark Hamiltonians in an inhomogeneous orthosymplectic superalgebra arXiv · Sep 29, 2026The paper constructs a supersymmetric factorization of generalized driven anisotropic Rabi–Stark Hamiltonians using an affine factor in an inhomogeneous orthosymplectic superalgebra. The normal product has an exact zero-energy ground doublet and a Witten index of two. It also covers a Bargmann hierarchy, endpoint conditions for exceptional finite-polynomial states, several limiting cases, and an interior example with additional drives, Stark deformation and intensity-dependent coupling.

Evanescent-wave Johnson noise from superconductors, explained

2026-09-29T00:00:00+09:00

Evanescent-wave Johnson Noise from Superconductors arXiv · Sep 29, 2026This paper calculates evanescent-wave Johnson noise above a superconductor's surface and the resulting relaxation time T1 of spin and charge qubits placed nanometers away. It uses a microscopic current-response kernel for a BCS superconductor, together with the fluctuation-dissipation theorem and nonlocal surface impedances. Magnetic noise is enhanced just below Tc by the coherence peak and falls exponentially at lower temperatures, while magnetic impurities produce a zero-temperature noise floor. ★★★★ Notable: Presents a theory of evanescent-wave Johnson noise and near-surface qubit T1 above superconductors, predicting a magnetic-noise coherence peak below Tc, a zero-temperature noise floor from magnetic im

How work cumulants scale when a driven Gaussian field crosses over between regimes

2026-09-29T00:00:00+09:00

Crossover of Scaling Behaviors of Work Cumulants in a Driven Gaussian Field Theory arXiv · Sep 29, 2026The paper derives the finite-temperature characteristic function of work for a driven O(N) Gaussian field theory and gives closed-form expressions for all zero-temperature excess-work cumulants. For gapped protocols, adiabatic perturbation theory yields a τ_Q^-2 scaling, where τ_Q is the protocol duration. For power-law protocols approaching criticality, the authors analyze the competition between critical excitations and regular contributions, identifying Kibble–Zurek-type scaling and a logarithmic correction at a specific threshold.

Dynamical resource theory of time-reversal symmetry breaking

2026-09-29T00:00:00+09:00

Dynamical resource theory of time-reversal symmetry breaking arXiv · Sep 29, 2026The paper proposes an operationally meaningful framework for quantifying the intrinsic time-reversal symmetry breaking (T-violation) of quantum channels, treating it as a resource within dynamical resource theory. T-violation is split into kinematic T-violation, arising from antiunitary motion-reversal, and nonunitality driven purely by thermodynamics. The authors also analyze the resulting resource theory of kinematic T-violation and report a universal golden unit, including for classical channels.

Puncturing method for adaptive entanglement-assisted quantum error-correcting codes

2026-09-29T00:00:00+09:00

Puncturing for Adaptive Entanglement-Assisted Stabilizer Codes arXiv · Sep 29, 2026This paper extends a puncturing construction for standard stabilizer codes to entanglement-assisted codes, so that one mother code can be adjusted to different numbers of available pre-shared Bell pairs. The three-step procedure treats the code as unassisted, punctures one receiver-side qubit, and recovers an entanglement-assisted form, reducing the required Bell pairs by one while keeping transmitted and logical qubit counts. The authors derive a bound on the resulting distance loss and give conditions for preserving the original distance. In an analysis of random codes with five to eight transmitted qubits, 14.75% had greater distance than their unassisted counterparts, and 81.4% of those admitted a puncturing choice that keeps the original distance.