In briefQuantum state revivals and time quasicrystals in a Fibonacci-driven central-spin model
SummaryThis paper studies a Fibonacci-driven central-spin model with Ising interactions, aiming to achieve perfect revivals and time quasicrystals without disorder. The authors show analytically that at a tuned interaction strength of 2mπ, no entanglement forms between central and satellite spins at stroboscopic times, producing long-lived quasiperiodic magnetization oscillations. Near Clifford points, the system also exhibits steered entangled dynamics that generate Bell-cat and spin-cat states, which the authors suggest could enable Heisenberg-limited metrology.
Anushka Agrawal, Adithya A. Vasista, Tanay Nag et al.
In briefGeometric views on fault-tolerant quantum computing
SummaryThis paper studies fault tolerance from three geometric perspectives. The authors build an operator-algebraic version of the fiber bundle framework and show that a generalized Knill-Laflamme condition implies a flat connection on it. They extend the framework to Gottesman-Kitaev-Preskill (GKP) codes, showing that each polarization type's moduli space embeds smoothly into a Grassmannian of a regularized distribution space. They also show that GKP codes tied to Jacobians yield magic states via code space projection of Gaussian states, identifying a CCZ-type example.
In briefFast, accurate rare-event simulation for quantum codes using MCMC with cluster moves
SummaryThis paper estimates logical error rates of quantum error-correcting codes at very low error rates, where direct Monte Carlo sampling is too expensive. The authors propose a new Markov chain Monte Carlo kernel combining locally balanced one-bit-flip proposals with a cluster-exchange move, since one-bit flips can get trapped on some codes and bias the estimate. Benchmarks on twelve codes show the new kernel matches a reference on every code, runs faster than one-bit flips where they are trapped, and beats direct Monte Carlo at the lowest error rate.
In briefBenchmark of quantum-annealing methods for factory layout planning
SummaryThis paper benchmarks four quantum annealing (QA) approaches for factory layout planning, including iterative binary quadratic, hybrid discrete quadratic, hybrid constrained quadratic, and hybrid nonlinear models. They are compared with a genetic algorithm, particle swarm optimization, and a hybrid tabu search and simulated annealing method on 14 layout instances. The QA approaches show competitive solution quality and reduce computation time by up to 94.51%. The iterative binary quadratic model obtains the best solution quality in 78.6% of instances.
Xiangqian Wu, Philipp Schworm, Marcel Wagner et al.
In briefReal-space electron-photon entanglement from quantum electrodynamics
SummaryThis paper studies the entanglement between an electron and the photon it scatters, resolved in real space and time. The authors solve truncated one-photon coupled equations numerically for a one-dimensional model atom in a waveguide, driven by a short off-resonant laser pulse. Global entanglement is largely transient, peaking during the pulse and then decreasing.
In briefMultistable and frustrated superradiant phases in an open anisotropic quantum Rabi trimer
SummaryThis paper studies the nonequilibrium steady states of an open anisotropic quantum Rabi trimer using semiclassical and quantum mechanical methods. It finds that the frustrated superradiant phase can be stabilized by both positive and negative photon hopping, and identifies separate dissipation thresholds for the normal and frustrated phases. The authors also report a finite-fluctuation critical exponent for the frustrated phase, with multistability tunable by anisotropy and dissipation.
In briefPopulation capacities and thermomajorization geometry for state conversion
SummaryThe paper studies which quasiclassical states can be converted into one another under thermal operations. It defines population capacities, the maximum population thermal operations can concentrate on each set of energy levels, and shows these form a submodular rank function whose base polytope is the thermally reachable region. The capacities yield exact conversion certificates and an optimal trace-distance error for approximate conversion.
WhyRecasts thermomajorization as a submodular rank function with a base polytope, giving a unified exact and approximate conversion characterization; impact stays within quantum thermodynamics.
In briefMultimode continuous-variable quantum key distribution built on CMOS-compatible photonic-electronic integration
SummaryThis paper presents a CMOS-compatible photonic-electronic multimode continuous-variable quantum key distribution architecture, using polarization multiplexing as a two-mode example. Silicon-photonic transmitter and receiver chips prepare and detect two polarization modes in parallel, with the receiver co-integrated with a 28-nm CMOS amplifier. The paper also gives a multimode security analysis that accounts for mode crosstalk. Over 10 km of deployed fibre, the mean finite-size key-rate estimate is 6.69 Mbit/s, 12 percent above the single-mode analysis.
In briefMultipartite quantum dynamics continuing after bipartite entanglement settles
SummaryThis paper studies whether multipartite correlations in quantum thermalization keep evolving after bipartite entanglement has equilibrated. The authors show that the full Schmidt spectra of a fixed tripartition can become stationary while local-unitary-invariant multipartite correlations continue to change. This separation is reported in self-dual kicked-Ising dynamics and asymptotically in Haar-random circuits. The authors also show that quantum error-correcting codes can independently tune the timescale of multipartite dynamics.
In briefFaster preparation of thermal and ground states for free fermions using a system-bath coupling
SummaryThe paper presents methods for preparing thermal and ground states of free fermions by engineering local interactions between the system and a bath whose size scales with the system. For thermal states at fixed inverse temperature and bounded bandwidth, the algorithm reaches trace-norm error ε in total simulation time Õ(√N/ε). Ground state preparation for gapped systems takes polylog(N/ε) time. The authors also give lower bounds for thermal state preparation within the bath protocols considered.
WhyAchieves sublinear simulation time for free-fermion state preparation via scaled bath, overcoming a linear barrier, with theoretical lower bounds supporting the claims.
In briefHow amorphization depth affects bismuth redistribution and activation in silicon for quantum devices
SummaryThe 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.
Youcef A. Bioud, Simon-Jean Michel, Sebastien Francoeur et al.
In briefMeasurement-dependent reduction of open dynamics in quantum phase estimation
SummaryThis paper studies the smallest set of observables needed to predict the full output distribution of the quantum phase estimation algorithm when its counting register evolves under open dynamics. Using general Krylov reduction theory, the authors explicitly determine this space for the full Fourier measurement and give an exact dimension formula with attainable bounds. They also treat approximate reduction via a finite-time Gramian and an a posteriori error estimate. Numerical calculations check the consistency of the representations and the error behaviour under non-Toeplitz perturbations.
In briefRecognizing phone signals by their spectral fingerprints using Rydberg atom sensors
SummaryThis paper presents a quantum radio-frequency sensing framework that combines Rydberg electromagnetically induced transparency spectroscopy with deep learning to classify mobile signals. The authors measured cellular voice call, Wi-Fi, and 5G emissions to build a spectral-fingerprint dataset and trained a convolutional neural network on it. A progressive fine-tuning strategy is used to handle spectral drift, and continuous real-time monitoring under changing wireless conditions is demonstrated.
In briefHybrid quantum-classical method for jointly optimizing bidirectional EV charging and trip assignment
SummaryThis paper addresses the joint optimization of bidirectional (V2G) charging schedules and trip assignments for electric vehicle fleets, a problem that is NP-hard. It proposes a hybrid quantum-classical Benders decomposition framework that uses logic-based conflict cuts requiring near-zero auxiliary qubits, along with a sparse recursive state-of-charge formulation. The authors report recovering MILP-optimal solutions on benchmark instances with a low auxiliary-qubit budget. They also run a small instance end-to-end on IBM quantum hardware as a proof of concept.
Mustafa Musab, Sebastian Schmitt, Markus Wappler et al.
In briefA Bargmann-invariant test for quantized gravity via the graviton commutator
SummaryThe paper proposes that the phase of a Bargmann invariant from two matter-wave interferometers can signal quantum gravity, since no branchwise-definite classical gravitational field can reproduce it. For matter linearly coupled to linearized gravity, the interference coherence factorizes into a Newtonian phase, the graviton state's characteristic functional, and a commutator phase. The authors argue that decoherence alone cannot prove gravity is quantized, because the first two terms are classically reproducible for Wigner-positive graviton states. The Bargmann phase isolates the commutator term, which is independent of the graviton state. For gravity this effect is far below experimental reach, but trapped-ion analogs could test it at order unity.
In briefA control-line multiplexing method for scaling up quantum computers
SummaryThe paper proposes a hybrid multiplexing framework that uses polychromatic microwave pulses and band-pass filters to control all gate operations by frequency-division multiplexing. This reduces the required number of control lines by one to two orders of magnitude. In a 1:4 demonstration, parallel FDM CZ gates reached average errors of (6.4±0.2)×10⁻³ and parallel FDM XY(π/2) gates reached (10.6±0.2)×10⁻⁴, with no statistically significant degradation from multiplexing.
WhyProposes all-microwave frequency-multiplexed gate control filling the two-qubit gap, with a 1:4 demonstration of parallel CZ and XY gates, though scale is modest.
In briefError bounds for basis-set size in quantum chemistry simulation
SummaryThis paper rigorously analyses how the error in quantum simulations of electronic structure depends on basis-set size N. It shows the ground-state energy error scales as O(N^{-1}) for plane-wave and spatial grid bases. For time evolution, the error in smoothed particle-position observables scales as O(N^{-5/3}+tN^{-1}), while the kinetic energy error scales as O((t+log N)/N).
Dominic W. Berry, Arkin Tikku, Sophia Simon et al.
In briefEstimating Photometric Redshifts with a Hybrid Quantum Neural Network
SummaryThis paper applies a Hybrid Quantum Neural Network (HQNN) to estimate photometric redshifts of galaxies, using data from the KiDS and VIKING surveys covering optical to near-infrared wavelengths. The HQNN's results are compared with those of a classical neural network. The HQNN recovers reference redshifts with high statistical fidelity, and its R² and MSE are consistently better than the classical model, though within the error range.
Giuseppe Sarracino, Vincenzo Fabrizio Cardone, Irene Graziotti et al.
In briefQuantized-resonance modeling of an emitter in a lossy multimode cavity
SummaryThis paper studies how a single atom behaves in a one-dimensional lossy resonator, where it can couple to several resonant field modes at once. The authors simulate the atom's dynamics using a resonance quantization formalism developed by Weitzel et al. (2026). They find that the minimum number of modes needed to capture the key features grows with coupling strength, and that the atom's dynamics depend strongly on its position in the multimode regime.
In briefExact limits on how internal and external entanglement trade off in two-mode Gaussian states
SummaryThis paper characterizes the exact trade-off between internal entanglement (negativity between two modes) and external entanglement (negativity across a Gaussian purification) in asymmetric two-mode Gaussian states at fixed local symplectic eigenvalues. The authors determine analytically the boundary of the attainable region, which numerical sampling first suggested, and prove that every point in the resulting admissible interval corresponds to a physical covariance matrix. They obtain sharp bounds on internal negativity, a saturated monogamy-type inequality, and recover the symmetric-state limit.
In briefHow electric fields change information content in confined quantum atoms, static versus time-dependent
SummaryThis review examines how external electric fields alter the information content of spatially confined atoms, comparing a uniform static field with a monochromatic time-dependent laser field. The analysis uses the sum of Shannon entropies in position and momentum space, studied in a confined hydrogen atom and a particle in a spherical box. Reported values include ground-state polarizabilities, which show that the entropic response differs markedly between the two systems.
In briefComparing classical and quantum solvers for QUBO problems, and whether solver selection can be reliably guided
SummaryThe paper compares classical, tensor-network, and fixed-schedule quantum solvers on 180 QUBO benchmark instances and on harder synthetic instances with known optima of up to 128 variables. A branch-and-cut solver matches all reference energies on the main benchmark, but on instances with relocated optima at 48 variables it finds only four of ten and certifies none, while parallel tempering finds every optimum. The authors find that their diagnostics do not yield a validated solver-selection rule, and the tested linear-ramp QAOA gives no solution-quality gain over classical methods.
Gerhard Hellstern, Cedric Schacht, Martin Zaefferer
In briefFaster generation of measurement counts for quantum circuit simulation via multinomial sampling
SummaryClassical simulators of quantum circuits often spend significant time drawing individual measurement outcomes (shots), with cost growing linearly with the shot count. This paper proposes drawing the measurement counts directly from a multinomial distribution, decomposed into conditional binomial draws that the BTPE algorithm performs in expected constant time. The sampling cost is therefore independent of the number of shots. Compared with Qiskit's sampling primitives for up to 20 qubits and 10^6 shots, the implementation was faster in every configuration tested, and its samples were statistically indistinguishable from the reference implementations.
In briefA self-correcting 3D surface code whose local dimension grows with system size
SummaryThe paper constructs self-correcting 3D surface codes over Z_q, where the local dimension q grows with system size. The model keeps the local geometry and stabilizer support of the ordinary 3D surface code and changes only the Pauli powers of the stabilizers. The authors prove that below the critical temperature, with q=Θ(N), memory times in both error sectors grow at least as exp[Ω(N^{1/3})], and numerical results support this.
WhyGrowing local dimension yields self-correcting 3D surface codes with proven exponential memory times, supported by numerical results.
In briefFrom single NV spins to ensembles: a calibrated symbolic regression pipeline for NV spectroscopy
SummaryThe paper presents a symbolic-regression pipeline that selects Hermitian operator terms from single nitrogen-vacancy center spectra, fits their coefficients, and combines the individual spectral responses into a calibrated ensemble model. The calibration accounts for resonance shifts, local disorder, orientation, and optical response. On public data, the zero-field held-frequency error fell by 56.2% relative to matched uncorrected composition. In simulated ensembles, models calibrated at 0 and 3 mT predicted an independently held-out 5.17 mT spectrum.
In briefA charge-coupled device method for generating arbitrary waveforms to control qubits
SummaryThis paper proposes an arbitrary waveform generation architecture for qubit control based on charge-coupled devices (CCDs). Waveform samples are stored as charge packets and clocked out as voltage samples, with multiple channels operated in parallel and interleaved to raise the effective sampling rate. The baseband waveforms are then upconverted to microwave frequencies to drive qubit operations. The authors state that representing waveforms as stored charge rather than continuously generated microwave signals could reduce cryogenic interconnect density and heat load in scalable quantum control systems.
In briefTesting whether a quantum state-over-time lies in its cone is NP-hard
SummaryThe paper studies the convex cone generated by "states over time," operators pairing a quantum state with a channel. It shows that a bipartite separable cone sits inside this cone as an exposed face, so separability's NP-hardness transfers to exact and weak membership and optimization. It also notes that, for certain dimensions, the cone admits no finite semidefinite representation.
WhyEmbeds the separable cone as an exposed face, proving NP-hardness of membership for the cone of states over time with rigorous reductions and a semidefinite-representability limit.
In briefHeisenberg-limited quantum metrology of electron-light coupling using multi-electron PINEM
SummaryThis paper examines the precision limit for estimating coupling strength in multi-electron photon-induced near-field electron microscopy (PINEM), showing that quantum Fisher information scales quadratically with electron number. It proposes a scheme using squeezed-light probing and homodyne detection that achieves Heisenberg scaling when electrons have nonzero inter-electron coherence. The authors also analyze how imperfect electron preparation causes phase noise and introduce an auxiliary optical mode to suppress this noise and recover the scaling.
In briefControlling and protecting two-qubit entanglement using two interacting oscillators
SummaryThis paper studies how tunable interactions between two auxiliary harmonic oscillators can control and protect entanglement between two qubits. Using a characteristic-function method, the authors derive analytical solutions and identify regimes of entanglement revival, suppression, and decay. They also examine thermal dissipation and report that suitable oscillator couplings can preserve substantial entanglement under the dissipative conditions considered.
Pablo Carlos L\'opez V\'azquez, Andr\'es Garc\'ia, Josu\'e Romero
In briefUsing LLMs to Translate Quantum Code Between Software Frameworks: An Exploratory Study
SummaryQuantum software development is complicated by quantum-mechanical semantics and fragmented software development kits (SDKs), which make translating code across SDKs difficult. The authors propose an LLM-based workflow for translating executable quantum programs between high-level SDKs, designed around quantum semantics and ecosystem version changes. In a preliminary evaluation of four LLM configurations on 43 tasks translating Qiskit programs to PennyLane and Q#, zero-shot Pass@1 reached up to 72.33%, and one-shot prompting further improved results.
In briefA general framework for how matter alters Leggett–Garg violation in neutrino oscillations
SummaryThis paper studies the four-time quantity K4 for two-flavor neutrino oscillations, using a pseudo-density matrix under static conditions rather than noninvasive measurement. It applies a Horodecki-type criterion to the temporal Pauli-correlation tensor. Explicit evaluations for flavor measurements in constant-density matter show that matter effects change the temporal correlations, with a pronounced matter–vacuum difference near the MSW resonance for the chosen parameters.
In briefHelicity-selective coupling of chiral phonons to PT-partner electron states in bilayer MoS₂
SummaryThis paper theoretically and computationally studies how chiral phonons interact with electron doublets degenerate under parity-time (PT) symmetry in 2H-bilayer MoS₂. PT symmetry suppresses the chirality of phonon singlets, but chiral phonon doublets can interact helically with PT-partner electronic states through a mechanism similar to pseudospin. Selection rules are analyzed using both PT and C₃ symmetries. The results suggest chiral phonons could be used to resolve intravalley electronic states in PT-symmetric systems.
In briefA measure for how much a set of quantum states shares coherence in one basis.
SummaryThe paper studies set coherence, which describes whether a collection of quantum states fails to be simultaneously incoherent in a common basis. The authors build an axiomatic framework for set-coherence measures and check which robustness-based measures satisfy its axioms. They also propose measures based on pairwise commutators and show that the amount of set coherence closely reflects performance in optimal approximate quantum broadcasting.
In briefQuantum ordinal selection using two comparisons
SummaryThe paper studies the best possible probability of picking an item within a set rank threshold, using at most two noiseless coherent pairwise comparisons of an unknown strict order. The authors build a comparison-specific semidefinite model that fully determines the achievable success and use computer-assisted proofs to find exact optima for seven objects and for minimum selection with eight objects. They construct an explicit algorithm family for minimum selection, whose asymptotic success is within 0.016% of the unrestricted optimum, and prove that this relative gap has a strictly positive limit.
In briefTarget Detection with Asymmetric Gaussian Classical Correlation
SummaryThis paper studies two-mode classical correlations in the Gaussian regime, generated by sending a thermal state through a beam splitter, and explicitly analyzes how measuring one mode affects the other, enabling a distinction between classical and quantum correlations. It shows that asymmetric classical correlations, with different mean photon numbers in signal and idler modes, are advantageous for target detection. Under on-off detection, classically correlated states significantly outperform quantum correlated states as the environmental thermal mean photon number increases.
In briefRank-one factored gradient descent for quantum pure-state tomography without restricted isometry
SummaryThe paper studies factored gradient descent, a scalable method for recovering low-rank positive semidefinite matrices, applied to quantum pure state tomography on multiple qubits. It shows that the restricted isometry property usually needed for guarantees fails under partial-weight Pauli measurements. The authors instead group commuting observables by measurement setting and introduce a max-sliced total-variation loss, with theoretical claims about spurious local minima and global optimality, checked numerically on four qubits.
In briefNeutrinos as Quantum Information Carriers? A Gap Analysis Against DiVincenzo Criteria
SummaryThis short paper is a gap analysis that checks neutrinos against the seven DiVincenzo requirements for quantum computing, using existing literature. It compares neutrinos on five computation requirements and two communication requirements. The authors find that neutrinos have high fidelity and good coherence but lack a clear qubit definition, initialisation, universal gates, individual qubit readout, and stationary-to-flying conversion. They conclude that neutrinos are best viewed as an exceptional flying information carrier, though very difficult to control.
In briefQuantum neural classifiers for detecting anomalies in network traffic
SummaryThis paper examines whether quantum machine learning can help detect anomalies in network traffic, testing four Variational Quantum Classifier designs on a synthetic traffic dataset. Deeper circuits reached higher accuracy but were more sensitive to training conditions, and the best configuration combined a ZFeatureMap with a RealAmplitudes ansatz optimized with ADAM. Classical models such as Support Vector Machine and Random Forest performed better on this synthetic data. The authors suggest quantum approaches may still be useful for noisier, higher-dimensional problems.
Mir H M Ilham, Hardique Dasore, Abdulrahman Ababneh et al.
In briefHigher-order OTOCs in chaotic quantum maps: resonances and asymptotic freeness
SummaryThis paper studies higher-order out-of-time-ordered correlators (OTOCs) in quantum maps, which measure how information scrambles and serve as a chaos diagnostic. Numerically, at intermediate times odd-order OTOCs decay at the classical rate set by the leading Ruelle-Pollicott resonance, while even-order ones decay twice as fast. Introducing decoherence through a coarse-grained superoperator restores a decay rate proportional to the order. At long times each higher-order OTOC is dominated by a single free cumulant whose saturation value scales inversely with Hilbert space dimension, indicating asymptotic freeness.
Nicol\'as G\'omez Brucks, Ignacio Garc\'ia-Mata, and Diego A. Wisniacki
In briefDigital twin for quantum repeater memories that accounts for model uncertainty
SummaryThe paper presents QMemTwin, a physics-constrained digital twin that estimates stored entanglement in quantum repeaters. It calibrates a bank of contractive passive state-space models and combines them using finite-sample-corrected Akaike weights. The method abstains when temporal-holdout data indicate unsupported dynamics. The reported numerical results are left as unfilled placeholders in the source text.
In brief"Wave Is All You Need": A Quantum Language Model Using a Fully Connected Quantum Boltzmann Machine
SummaryThis paper proposes a self-attention mechanism based on the fully connected quantum Boltzmann machine (FC-QBM) and builds a language model, FC-QBM-LM, around it. An 8-qubit model was trained on a Tang poetry corpus, with the quantum layer handling positional encoding and self-attention using only 44 parameters. The model converged well without noise and kept over 99% of its noiseless convergence performance across eight noise levels. Five-character quatrain generation experiments showed preliminary associative and divergent thinking abilities.
In briefQQLink: A declarative framework for coordinating quantum workflows across multiple QPUs
SummaryThe paper presents QQLink, a programming and orchestration layer that lets one program express measurement-based dependencies across quantum nodes and automatically derives the required coordination. Its planner builds an acyclic dependency graph, and the same programs run on simulators or are lowered to dynamic circuits on partitioned hardware. The authors evaluate seven protocol workflows on simulators and run plans on two IBM Heron processors, reporting correctness results alongside hardware limitations. Execution across physically networked QPUs is left as future work.
Vicente Leyton Ortega, Narasinga Rao Miniskar, Thomas Naughton et al.
In briefReal-time tracking of qubit relaxation, dephasing, and two-level defect dynamics in transmons
SummaryThis paper examines why superconducting transmon qubits show performance fluctuations over time, which limit gate fidelity. The authors observe correlated increases in relaxation and dephasing rates lasting minutes to hours, called T1 and T2 excursions. Using interleaved lifetime and coherence measurements, noise spectroscopy, and two-level-system spectroscopy, they find these excursions are caused by one or a few strongly coupled defects that spectrally diffuse into resonance with the qubit. The measurement protocol is presented as a tool for identifying noise sources behind these fluctuations.
Ambrose Yang, Alexander M. Young, Paal H. Prestegaard et al.
In briefPath integral control extended to the complex plane
SummaryPath integral control is a stochastic optimal control method that computes policies as weighted averages over state trajectories. This paper extends it to the complex plane using circular complex Wiener processes, with a change of measure defined under an exact control-noise matching condition. Applied to stochastic Schrödinger equations, the formalism handles paired non-Hermitian jump channels with unequal positive dissipation rates and yields cross-entropy-optimal feedback and open-loop control formulas.
In briefStrict Lower Limits on Atomic and Ionic Ground-State Energies
SummaryThe paper introduces an iterative method for computing rigorous lower bounds on the ground-state energies of all atoms and ions. The accuracy depends on the initial energy estimate and on the upper bound for the maximum number of bound electrons. The authors prove E(N,Z) ≥ -0.8710 N^{1/3} Z^2 for atoms and ions with Z ≤ N, improving the previously best known constant. They also compute bounds for all atoms with 2 ≤ N ≤ 86 and compare them with earlier results.
WhyIterative method sharpens the rigorous atomic ground-state lower bound constant from 1.1447 to 0.8710, compared against prior bounds for all atoms up to 86.
In briefSymmetry-resolved two-site entanglement as a probe of Mott and pseudogap physics in plaquette CDMFT
SummaryThe paper introduces a symmetry resolution of parity-superselected two-site entanglement, measured by fermionic negativity and relative entropy of entanglement, and extends it to full entanglement in pure and mixed states. The method is applied to the Hubbard model, first for a dimer and then for plaquette cluster dynamical mean-field theory. Tracking interaction- and density-driven Mott transitions at zero temperature, the authors show that the three symmetry-resolved components probe different aspects of Mott and pseudogap physics.
Gabriele Bellomia, Carlos Mejuto-Zaera, Massimo Capone et al.
In briefOptimal quantum adder that needs no ancilla qubits
SummaryThis paper constructs an exact n-bit quantum adder that uses no ancillary qubits, with O(n) gates and O(log n) depth. The circuit uses only X, CNOT, and Toffoli gates under all-to-all connectivity and is classically reversible. The authors state that both the gate count and the circuit depth are asymptotically optimal.
In briefEmergent Recursive Kernels in Quantum Reservoir Computing: a method for learning with fixed quantum reservoirs using simple recursive kernels
SummaryThe paper studies a fixed quantum reservoir made of an input coupling followed by a randomly sampled Haar unitary. In the large-dimension limit at fixed history length, the authors show it admits an exact recursive kernel that reduces to a scalar recurrence independent of reservoir size. The kernel coefficients are connected to out-of-time-ordered correlators, and tuning memory retention and interaction order adapts it to different tasks. On the NARMA10 benchmark, the tuned kernel gives lower prediction error than the tested Ising and SYK reservoirs.
In briefLoss-tolerant bosonic codes with capped photon occupation
SummaryThe paper studies Fock-state codes across q bosonic modes with total excitation N and at most B excitations per mode, where q is proportional to N. For each fixed cap B and ratio q/N above 1/B, it proves explicit achievable rates that are positive for sufficiently small loss fractions δ. At B=2 and q=N, the rate is positive for δ below 0.1355 and about 0.281 at δ=0.1, exceeding the previously known exact qutrit-code rate of about 0.275.
Avraham Kreindel, Aryeh Lev Zabokritskiy (Yohananov)
In briefPauli-ball discrepancy: a measure of how evenly quantum codes spread error images
SummaryThe paper introduces the Pauli-ball discrepancy, a quadratic measure summed over all error radii, of how uniformly the Pauli error images of a quantum code cover Hilbert space. At certain parameters, such as those meeting the quantum Singleton or one-error Hamming bounds, the discrepancy equals an explicit benchmark plus a nonnegative remainder. This remainder is used to bound fidelity-related error measures for recovery under noise.
In briefExactly Identifying Quantum Correlations in the Simplest Bell Setup
SummaryThe paper characterizes the boundary of quantum correlations in the minimal Bell scenario. It gives a computable necessary and sufficient criterion: a correlation is quantum if and only if it decomposes into an extreme quantum correlation plus a classical correlation. The authors also classify the maximal-face structures containing each nonlocal exposed point.
WhyGives a computable necessary-and-sufficient criterion for the quantum boundary, proving each quantum-advantage Bell functional has a unique quantum maximizer, resolving a long-open problem.
