In briefDeep-microscopic photonic band structure of a 2D honeycomb lattice, a theory resolving light at the lattice scale.
SummaryConventional macroscopic models of light in materials average the optical response over lattice structures and miss full spatial dispersion. This paper formulates a deep-microscopic nonlocal photon theory from the Maxwell Hamiltonian and its characteristic equation. It yields a photonic band structure with full spatial dispersion and real-space Bloch field textures. The theory is demonstrated on a two-dimensional tight-binding model of a gapped honeycomb lattice.
In briefGaps in Path Distinguishability at Fixed Visibility in Noisy Qubit Interferometers
SummaryThis paper studies the attainable range of path distinguishability and fringe visibility in a two-path interferometer whose path marker is a qubit, holding the source, preparation channel, path-dependent interaction and subsequent marker channel fixed. Varying only the marker input, the authors characterize the Helstrom-optimal distinguishabilities achievable at each feasible visibility. They show these form at most two closed intervals that can be separated by a gap, and give a geometric criterion for when a gap occurs, along with bounds under finite-resolution calibration errors.
In briefCoherent State Projection Eigenvalue Theorem: a quantum physics paper on symmetry in bosonic systems
SummaryThis paper proves an eigenvalue theorem for the continuum limit of projected coherent states, which extend coherent state representations of bosonic Hilbert space. The authors show that in this limit the projected coherent states are eigenstates of the symmetry-generating operator. The result yields phase-space differential identities that include the conserved eigenvalues. Applications to improved Fokker-Planck and stochastic equations are deferred to future work.
In briefKrylov geometry and optimal recovery under uncertain coherent noise: a study of the best achievable recovery from unknown coherent rotations in quantum codes.
SummaryThe paper determines the limit of recovering from a coherent rotation with an unobserved angle, given a known generator and calibration data. Two polynomial projections separate correctable error amplitudes from the part a coherent decoder can cancel. Under explicit rank and moment conditions, it gives the exact leading optimal entanglement infidelity at weak noise and a matching recovery. It also treats unknown angle distributions and a loss-free four-photon memory example.
In briefCompeting Fault Histories in Lattice-Surgery Decoding
SummaryDifferent physical faults can produce the same detector record while carrying opposite logical labels. The paper studies how this ambiguity affects a lattice-surgery parity measurement in a distance-three circuit, comparing single-gate faults with reset/readout pairs. At one noise point, the cost of keeping the selected single-fault decisions is bounded from below, and changing them helps at higher noise but hurts at low noise. The scope of this explanation is limited.
In briefAdmissible subspaces for collective Haar twirl and their heredity under reduction
SummaryThe paper studies which subspaces can serve as plaintext spaces for quantum private broadcasting, where a message is encrypted once and broadcast to several recipients. Using Schur-Weyl duality, the authors classify all subspaces on which the collective Haar twirl acts as a replacement channel, with explicit two-block and multiblock constructions. They also characterize privacy, design and QPB heredity under deleting a recipient, showing the symmetric tower is fully QPB-hereditary.
In briefWhen a bosonic operator defines a valid Hamiltonian
SummaryThis paper studies whether Hermitian polynomials in the quadrature operators x and p define a unique quantum dynamics in continuous-variable quantum information. The authors present an algorithm that determines, from the coefficients alone, whether such a polynomial gives exactly one, no, or an infinite family of distinct dynamics, and the family size. Gaussian operators always yield one dynamics, while non-Gaussian ones can yield the other outcomes even for simple Hamiltonians.
Felix Fischer, Hermann Schulz-Baldes, Daniel Burgarth et al.
In briefQuantum Solutions to the Closest String Problem Using NV-QWOA
SummaryThis paper presents an end-to-end quantum implementation of the Closest String problem, which seeks a string minimizing the maximum Hamming distance to a set of reference strings. It uses the Non-Variational Quantum Walk Optimization Algorithm (NV-QWOA) and gives gate-level circuits along with resource estimates for qubits and circuit depth. The authors also propose a problem-size-dependent prescription for the phase parameter γ that needs no instance-specific tuning. Simulations show the algorithm consistently amplifies optimal and near-optimal candidate solutions.
In briefCommunication Complexity of Singularity Testing for Integer Matrices
SummaryThe paper studies how many bits Alice and Bob must exchange to decide whether a matrix of k-bit integers, split between them, is singular over the rationals. It proves a bounded-error quantum lower bound and a randomized upper bound that match at Θ(n² log(nk)) when k ≥ n log n. For bitwise XOR sharing, it proves a quantum lower bound of Ω(n²k) that matches the trivial upper bound.
In briefExact limits linking Leggett-Garg test violations to negative quasiprobability weight
SummaryThe paper studies Leggett-Garg (LG) inequalities, which test whether correlations across different times can be explained by a positive joint probability distribution over histories. The authors derive a universal bound relating LG violations to the negative eigenvalue weight of spacetime density kernels. For any number of measurements, they give an exact relation for the minimum compatible kernel negativity, which is nonzero if and only if at least one LG inequality is violated.
In briefOpen quantum-dot battery charged by local dephasing
SummaryThe paper proposes an open quantum battery made of a triple-quantum-dot chain, with one end coupled to a thermal reservoir and the far dot strongly detuned as an energy store. Local dephasing autonomously drives the system into a nonequilibrium steady state with high ergotropic efficiency, which can approach unity. The charged state stays long-lived after the dephasing source is switched off. Two protocols for extracting the stored energy are demonstrated.
Alok Nath Singh, Rafael S\'anchez, Andrew N. Jordan
In briefControlling transport with structured long-range hopping
SummaryThis paper studies transport in a one-dimensional disordered chain with nearest-neighbor and long-range hopping. The long-range amplitudes may be uniform or random. Uniform long-range hopping strongly suppresses delocalization at weak disorder, while randomizing these amplitudes removes this low-disorder suppression and enhances transport.
In briefChecking whether noise-reduction methods make quantum optimization choose worse answers
SummaryThis paper tests whether zero-noise extrapolation (ZNE), a method that reduces noise in quantum computations, improves accuracy while leading to poorer parameter choices in QAOA for MaxCut. Simulations compare Richardson orders one to three against unmitigated estimates using both mean-squared error and decision regret. A frozen confirmation reproduced four conditions where error decreased but regret increased slightly. Results cover simulated exhaustive grids only, not hardware or optimizer loops.
In briefSemiclassical dynamics of higher-order squeezing: self-adjoint extensions and coherent returns
SummaryThis paper studies higher-order squeezing Hamiltonians, which have several self-adjoint quantum realizations, even though their classical trajectories reach infinity in finite time. The authors relate these extension problems through boundary amplitudes and the semiclassical propagation of coherent states, and use a discrete Fourier transformation to obtain the sink-to-source ray matrix of each realization. They show that after the first passage through infinity, the Husimi probability measure converges to point masses on outgoing classical branches, weighted by the squared moduli of the matrix entries.
SummaryThis paper examines a new class of distance-reducing hook errors in the triangular color code, called junction hook errors, which existing classification by anyon type does not capture. The authors verify for distances d=7, 9, and 11 that such errors exist and, together with single data qubit faults, can produce undetectable logical errors. They conclude that additional protection such as flag qubits is still needed to restore full circuit-level distance. The schedule still improves circuit-level distance to d-⌊(d+3)/6⌋.
In briefA new analytical result for the Born-Infeld integral potential
SummaryThe paper finds that the Born-Infeld potential at short distances from a charge can be almost exactly written as a Coulomb-type potential minus a Yukawa-type potential. This allows a physical reading in terms of classical vacuum polarization and an effective mass. The authors propose a new U(r) covering all space and use it to compute first-order energy shifts in hydrogen-like atoms in closed form. Comparing with high-precision spectroscopy gives a model-dependent lower bound on the maximum field parameter b.
Leonardo Paulo Guimar\~aes De Assis, Priscila Vald\^enia dos Santos, Sergio de Oliveira Vellozo et al.
In briefHow nonlinear electrodynamics shapes quasinormal modes of rotating black strings
SummaryThis paper studies massless scalar perturbations of rotating anti-de Sitter black strings sourced by a power-Maxwell field with negative exponent. Spectra are computed with three independent methods and checked against the planar Schwarzschild-AdS limit. At a reduced charge of 0.72626 the least damped modes meet on the imaginary axis, so more strongly charged strings ring down without oscillating. Rotation extends this exceptional point into a line, adds a purely damped axisymmetric tower, and produces no superradiant growth.
In briefTwirled and swirled worlds: a compositional approach to symmetry-restricted quantum theories
SummaryThis paper studies generalised probabilistic theories restricted by symmetry-imposed superselection rules, called twirled and swirled worlds. It treats states, effects and multipartite transformations uniformly as processes and defines group actions on whole theories. The authors establish when invariant subtheories satisfy process tomography and when ancillary systems or entanglement are needed. They also recover bilocal classical theory and real quantum theory as twirled and swirled subtheories of classical and complex quantum theory.
In briefVariational optimization to correct imperfect polarization qubit experiments
SummaryThis paper uses variational optimization to counteract hardware imperfections in quantum network nodes. The authors parameterize simple prepare-and-measure protocols and optimize them on an optical testbed as a proof of principle. They demonstrate automated polarization compensation with results comparable to conventional methods. The paper also analyzes the effects of hardware imperfections and dark counts and compares several gradient estimation methods.
Timur Javid, Brian Doolittle, Colin P. Lualdi et al.
In briefDesigning trial spaces for quantum simulation on noisy hardware
SummaryThis paper proposes choosing the basis for a quantum simulation by considering both the physical problem and device characteristics before fixing states and evolution times. Tests on many-body and molecular models show it can find useful directions that ordinary time evolution misses, though some directions may become too similar to estimate reliably. A four-qubit experiment over seven days reports a clear reduction in projected-energy error from problem-informed time choices compared with uniform sampling, serving as a proof of principle.
In briefQuantum-Relativistic Anomalous Proper Time: Exploring proper time values beyond classical general relativity if gravity and proper time obey quantum superposition.
SummaryThe paper examines unusual consequences of assuming that gravity and proper time follow the quantum superposition principle. It shows that a massive body in a superposition of two positions, post-selected in a suitable final state, can yield an effective proper time elsewhere outside the classical general relativity range, even becoming negative. The authors also propose an interferometer experiment under Earth's gravity to detect anomalous effective proper time linked to a quantum particle's internal degrees of freedom, which they say is feasible in principle with current technology.
In briefA New Non-Affine Family in the Karlsson–Szöllősi Intersection of Complex Hadamard Matrices
SummaryThe paper shows that, up to standard Hadamard equivalence, the intersection of Karlsson's K_6^{(2)} and Szöllősi's X_6^{(2)} two-parameter families equals the known affine Diţă curve D_6^{(1)} together with a new non-affine one-parameter family C_6^{(1)}. The authors give a new parametrisation of X_6^{(2)} in Karlsson coordinates and a constructive classification of the intersection. They suggest this may support the search for mutually unbiased bases in six dimensions.
WhyIdentifies a new non-affine one-parameter family in the Karlsson-Szöllősi intersection with a constructive classification, a substantive advance for six-dimensional complex Hadamard matrices.
In briefLocalization in a quantum lattice when only part of it is periodically driven
SummaryThis paper asks whether periodically driving only a subsystem can delocalize a localized quantum lattice that is fully driven to delocalization in the clean case. The authors study a two-leg ladder made of an Aubry-André chain coupled to a periodically driven clean tight-binding chain, using exact numerical calculations. They find that subsystem driving below a critical frequency does not achieve complete delocalization, instead producing a mixed phase where localized and delocalized states coexist.
In briefQuantum heuristic separation of comb inequalities for the travelling salesman problem
SummaryThis paper proposes a quantum heuristic algorithm for separating comb inequalities, important cutting planes in the travelling salesman problem. It prepares a uniform superposition of combs with a fixed number of teeth using polynomially many gates and qubits, then searches for violated inequalities with the Grover-Mixer QAOA. The authors show polynomial running time under prescribed budgets but give no evidence that those budgets suffice to find a violated comb with constant probability. Explicit circuits for the mixer, problem Hamiltonian, and resource analysis are provided.
In briefGenuinely multipartite entangled qudits: a single rule linking all link classes
SummaryThis paper studies multipartite quantum entanglement using an analogy with linked rings, asking which groups of particles stay entangled when others are lost. The authors recast link polynomials as hypergraphs and give an explicit formula for pure qudit states whose entanglement under any particle loss matches the link class exactly. They also determine which entangled groups are genuinely multipartite entangled and prove the conjecture that m-resistant pure qudit states exist for any number of particles and any m.
WhyGives an explicit construction matching link classes to pure qudit entanglement and proves a long-standing conjecture, with impact mostly confined to quantum network theory.
In briefDirectly testing conformal symmetry with Rydberg atoms: assessment and proposals
SummaryThe paper proposes a direct test of conformal symmetry using Rydberg-atom arrays arranged on a circle, by measuring equal-time two-point correlation functions against the form predicted by conformal field theory. The authors estimate the number of experimental snapshots needed for sufficient statistical precision. They also optimize the time-dependent ramp of the Rabi frequency and detuning used to adiabatically prepare the critical state, reporting higher fidelity over shorter times than earlier experiments. They conclude that such a test appears feasible with current Rydberg-atom technology.
In briefMaximal orbital entanglement from non-interacting fermions
SummaryThe paper proves that Slater determinants of N fermions on a lattice, though free of particle correlations, can carry up to min{d_A, d_B, N, d−N} ebits of orbital entanglement. With enough particles and holes, this equals the maximum over all fermionic states. The authors derive closed-form maximal orbital total correlations for all bipartitions, the finest partition, and partitions of up to five sites, using new majorization relations for Hermitian matrices.
WhyProves free-fermion Slater determinants can reach the maximal orbital entanglement of general fermionic states, with closed-form results.
Damiano Aliverti-Piuri, Julia Liebert, Christian Schilling
In briefIdeal interaction dynamics of defects and background fields in condensed matter
SummaryThis paper proposes a framework for the conservative coupled evolution of defect density and background fields in condensed matter. It applies the approach to two cases: Gross-Pitaevskii theory of quantum fluids and the Ericksen-Leslie model of nematic liquid crystals. The authors combine the Euler-Poincaré variational setting with gauge theory of topological defects to resolve ambiguities in defect density definitions. The method is presented as unified for cases without defect reconnection.
Fran\c{c}ois Gay-Balmaz, Tudor S. Ratiu, Cesare Tronci
In briefDistributed quantum-classical supercomputing with layered generative learning for molecular interactions
SummaryThis paper presents a distributed quantum-centric supercomputing framework that splits complex molecular problems into smaller parallel subproblems needing fewer qubits and shallower circuits. A two-step aggregation reconstructs the global solution, combining physics-informed generative SQD with a secondary generative module. For water and formamide dimers, the method reduces diagonalization dimension and improves energy accuracy over conventional SQD. For the water hexamer cage, a 120-qubit problem is split into six 20-qubit subsystems with results in good agreement with classical references.
Chayan Patra, Prayas Ghosh, Adwait Patkhedkar et al.
In briefLower-frustration block encodings for lattice Hamiltonians via patch routing
SummaryThis paper proposes a "patch routing" method for generating low-frustration block encodings of frustrated lattice Hamiltonians built from repeated local interaction patches. A small local patch is block-encoded once and then applied across the lattice coherently using a SWAP-style routing network, so the expensive local encoding cost does not grow with lattice size. The authors apply the approach to the Heisenberg, Fermi-Hubbard, and honeycomb spin-liquid models. For a 120×120 J1-J2 Heisenberg model they report a 15–17× reduction in leading T cost per qubitized-QPE run relative to prior Pauli LCU constructions.
WhyProposes patch-routing block encodings exploiting symmetries, reporting 3 to 17 times lower T cost than prior Pauli LCU constructions on several lattice models.
Minzhao Liu, Abeynaya Gnanasekaran, Ananth Kaushik et al.
In briefSome Quantum States Already Require Quantum Time Evolution
SummaryThe paper shows that testing consistency between a theory's state space and its dynamical laws can probe quantum time evolution. Within a class of generalized phase-space theories, certain quantum states can only belong to a theory if their evolution is quantum, otherwise anharmonic potentials would yield negative marginal distributions. It further shows that the first excited state of a harmonic oscillator alone selects the Moyal bracket to leading order in ħ².
In briefCreating entanglement in solids using split X-ray photons and resonant scattering
SummaryThis paper proposes an interferometric resonant inelastic X-ray scattering protocol that creates entanglement between spatially separated ends of a solid-state sample. An incident X-ray photon is split by a beam splitter to illuminate both ends, and the recombined, energy-selected scattered photon projects the material into a superposition of end excitations. The authors present this as an X-ray, solid-state analogue of the DLCZ heralding scheme and illustrate it with three models.
In briefOne-sided device-independent quantum key distribution secure against all attacks using any pure bipartite entangled state
SummaryThis paper studies one-sided device-independent quantum key distribution (1SDI-QKD), where one measurement device is trusted and the other is untrusted, using quantum steering as the resource. The authors show that a secure key can be obtained from any pure bipartite entangled state in this setup. Considering realistic detectors and sources, they find the critical detection efficiencies and visibilities needed to extract a secure key for each pure entangled bipartite state.
WhyShows any pure bipartite entangled state yields secure keys in 1SDI-QKD, removing reliance on maximal entanglement, with critical efficiency and visibility thresholds derived.
In briefDetecting nonclassicality from partial photon-number occupation data
SummaryThe paper presents a numerical method that builds optimal linear witnesses of nonclassicality from any subset of measured Fock-state occupation probabilities, solved as a semi-infinite linear program, without full state reconstruction. It includes known analytical criteria as special cases and generally detects larger nonclassical regions. An open-source implementation is provided. As a case study, the resonant Jaynes–Cummings model with thermal states shows nonclassicality at short interaction times and near thermal balance.
Martin \v{Z}onda, Pavel Bal\'a\v{z}, Luk\'a\v{s} Lachman et al.
In briefTraining quantum circuits entirely on a quantum computer using Quantum Hamiltonian Descent
SummaryThis paper proposes training parametric quantum circuits fully on a quantum computer using Quantum Hamiltonian Descent (QHD), where circuit parameters are encoded in qubits that coherently control the circuit. The authors prove that, for smooth periodic cost functions including those of parametric circuits, the simulation error is independent of grid resolution and grows at most linearly with the number of parameters. Simulations on benchmark functions and circuits show that the proposed schedules substantially increase the probability of finding the global minimum at equal cost.
In briefFermion Scattering on Quantum Computers: Simulating Resonant Particle Scattering on Hybrid Quantum Hardware
SummaryThis paper proposes a hybrid quantum-computing framework that encodes fermions in qubits and the scalar field in qumodes to study fermion-antifermion collisions in (1+1)-dimensional Yukawa theory. Near resonance, a localised scalar excitation forms and energy partially returns to the fermions, accompanied by enhanced entanglement. Measured decay rates agree with analytic predictions to within a few percent.
In briefA hardware-friendly way to estimate LCU-based expectation values by moving work to classical computers
SummaryThis paper introduces HERMES, a method for estimating expectation values of a quantum state evolved by a general operator A. It handles A classically by sampling Pauli terms, avoiding ancilla qubits and controlled unitaries. On H₂ and LiH ground-state energy estimation, it matches or beats a single-ancilla LCU baseline using shallow circuits, and it is more noise-robust, completing a noisy LiH simulation the baseline could not. The trade-off is classical overhead that grows with the number of Pauli terms in A.
In briefModular optical fault-tolerant quantum computing with a verified-resource and online-logic interface
SummaryThe paper proposes a factory–processor interface that separates code-dependent encoded-resource preparation from reusable online logical processing on a common Gaussian optical processor. As a concrete example, it combines an offline verified Bell-resource factory built on a recursively concatenated C4 code with physical GKP qubits and an online time-domain measurement-based quantum computation processor. Simulations report that logical Bell error rates decrease as the concatenation level increases, under the stated noise model and postselection policy.
In briefThe Real Cost of a Grover Oracle for Minecraft Seed Search on Quantum Hardware
SummaryThe paper estimates the resource cost of a Grover oracle used to recover Minecraft 1.13.1 world seeds, comparing versions with and without specialized known-constant arithmetic. Direct Fourier-basis constant arithmetic reduces the placement-predicate qubit width and the scaling of two-qubit gate counts, and the representative circuit's qubit, CX, and depth counts drop substantially. The authors also ran reduced-width circuits in complete Grover loops on IBM and Quantinuum hardware, finding that compiled hardware behavior depends strongly on routing and execution context.
In briefMinimal unitary representations of causal quantum channels in time-invariant systems
SummaryThis paper studies quantum channels that respect causality in single-input-single-output linear time-invariant systems. It describes them using positive semidefinite Schur-class kernels acting through multiplicative maps, and shows these admit a minimal analytic Stinespring representation. The authors also give a stability criterion for two-sided inner completions and algorithms to compute them when the McMillan degree is finite.
In briefHardware-aware quantum circuit compression using Weyl-chamber structure
SummaryThis paper studies tensor-network-based quantum circuit compression for simulating quantum many-body dynamics on near-term hardware. The authors find that Riemannian-optimized two-qubit gates show a predictable Weyl structure, near R_ZZ for the Ising model and near fSim for the Heisenberg XXZ model. They compare optimizing directly over the native gate set with optimizing generic unitaries, concluding that small residual Weyl parameters are essential for high compression of the Ising propagator, while the Heisenberg propagator can use the native XXZ structure to build a more efficient circuit.
Neel Misciasci, Isabel Nha Minh Le, Christian B. Mendl
In briefLimits on information causality violations using single-copy protocols
SummaryThis paper studies how information causality constrains bipartite post-quantum nonlocal correlations. The authors formulate the single-copy problem as an optimization over all protocol parameters and prove a deterministic simplification. For correlation families closed under wirings, excluding single-copy violations suffices to exclude all finite-copy adaptive-protocol violations.
WhyProves a reduction from adaptive multi-copy to single-copy protocols and characterizes CHSH macroscopic locality via second-order expansions, a strong theoretical advance.
In briefQuantum Machine Learning for Medical Imaging: A Radiologist's Introduction
SummaryThis review introduces radiologists to core quantum computing concepts, such as qubits, superposition, entanglement, and quantum circuits, along with current noisy intermediate-scale quantum hardware. It summarizes quantum machine learning models and image representations used in medical imaging, and reports applications including brain tumor classification, pneumonia detection, and CT and PET reconstruction. The authors note that most published systems are hybrid quantum-classical pipelines tested on small datasets or simulators, so clinical deployment is not yet feasible.
Ruben Ortiz Cordero, Gaven K. Smart, Harshada Gothankar et al.
