In briefExact quantum circuit counting how many qubits are 1, at optimal depth and width
SummaryThe paper builds an exact quantum circuit that computes the Hamming weight (the number of 1s) of an n-qubit register with depth O(log n) and size O(n log n). It uses only the n input qubits plus ceil(log2(n+1)) binary output qubits, and both depth and total width are stated to be optimal. The authors also give exact circuits for all symmetric Boolean functions and apply the counter to prepare balanced Dicke states for even n.
In briefGround states heating unusually fast in dephased SU(N) spin systems
SummaryThe paper studies SU(N) ferromagnetic spin chains with local dephasing and reports a strong quantum Mpemba effect, in which the ground state heats faster than every Gibbs state at finite positive temperature. An energy-resolved sign criterion is derived, and the effect is confirmed by an exact finite-chain solution and symmetry-resolved calculations in larger spin-one chains, including nonintegrable exchange.
In briefFully quantum fidelity-based entropic continuity bounds for quantum conditional entropies
SummaryThis paper gives a continuity bound for quantum conditional entropies expressed in terms of fidelity, independent of the conditioning system's dimension. It covers the von Neumann entropy and one version of sandwiched Rényi entropy, relevant to quantum key distribution. The authors state the bound should improve on earlier trace-distance-based continuity bounds in such applications. They also show the bounds can be sharpened for classical-quantum states, hold for countably infinite-dimensional conditioning systems, and present variants for exponentials of Rényi entropies.
In briefDe Finetti Structures in Quantum Networks: how reduced states of subsystems in large quantum networks converge to a standard form
SummaryThis paper studies N identical quantum systems on a graph's vertices, coupled pairwise along edges, with K vertices designated as the system of interest and the rest as a reservoir. Under generic connectivity between them, the reduced state of the system converges, as N grows, to a convex combination of symmetric product states, a de Finetti representation. The authors construct this representation explicitly, quantify the convergence rate, and show Erdős–Rényi random graphs exhibit the structure.
In briefUpper bound on correlation energy of dense Fermi gases
SummaryThis paper proves that the random phase approximation gives an upper bound on the correlation energy of a three-dimensional, weakly interacting Fermi gas in the thermodynamic limit at high density. It uses a mean-field scaling and a correlated trial state built from collective particle-hole excitations on Fermi surface patches via a quasi-bosonic Bogoliubov transformation. The key step controls the position-space localization of these excitations, and an iterated Duhamel expansion reduces the problem to an effective quadratic Hamiltonian that is approximately diagonalized.
WhyRigorously proves an RPA upper bound on correlation energy for dense Fermi gases in the thermodynamic limit using localization and iterated Duhamel expansion.
Niels Benedikter, Sascha Lill, Marcello Porta et al.
In briefError from discretizing space in quantum chemistry simulation
SummaryThis paper studies the spatial discretization error that arises when a continuous quantum chemistry problem is approximated using a finite basis and a truncated spatial domain. The authors develop a Sobolev-Galerkin framework for unbounded Hamiltonians and derive error estimates for wave-function dynamics and ground-state energies in many-body Coulomb systems. Ground-state energies converge at a sharp rate of M^-1 at fixed cell size, and the work combines these bounds with quantum algorithms to give end-to-end complexity bounds.
WhyIntroduces a general Sobolev-Galerkin framework with sharp M^-1 ground-state rates and first rigorous end-to-end quantum simulation complexity bounds.
In briefLow-temperature response theory for weakly interacting quantum spin systems
SummaryThis paper derives response theory at positive temperature for a class of weakly interacting quantum spin systems. It extends earlier rigorous results for lattice fermions to non-Fermi systems. The proof relies on local indistinguishability, a locality property needed for low-temperature adiabatic expansions, which was established previously with Adhikari using cluster expansion and a probabilistic swapping trick.
In briefNoise-Awareness in Quantum Software Testing: An Empirical Landscape Analysis
SummaryThis paper systematically reviews 61 quantum software testing papers from 2018 to 2025 to assess whether they account for noisy hardware execution. It finds that 77.0% are noise-oblivious and only 18.0% evaluate on physical hardware or a noisy simulator. The authors also show that many noise-aware papers still evaluate only on ideal simulators.
Mir Mohammad Yousuf, Shabir Ahmad Sofi, Bisma Majid
In briefLiftDiff: A guided diffusion method for discovering quantum error-correcting codes
SummaryThis paper introduces LiftDiff, a generative approach for discovering quantum error-correcting codes. A discrete diffusion model generates base matrices over a group algebra, which are expanded into lifted product codes, with an energy function guiding the sampling toward favorable code properties. The authors report several newly discovered codes, and some outperform the Gross code across a range of tested physical error rates.
In briefMachine learning detection of simulated attacks on QKD systems using aggregated logs
SummaryThis paper introduces QF-LOG, a simulation-based forensic framework that classifies normal QKD operation and three simulated attacks using four aggregated log features: QBER, photon count, latency, and abort flag. On a 5 million-record synthetic dataset, full-feature machine learning models reached macro F1-scores of about 0.82, outperforming a transparent baseline. However, on a dataset generated with shifted simulated operating parameters, scores fell to about 0.56, showing that stable internal results do not guarantee reliability under changed conditions.
Madhab Chandra Das, Sajid Ahmed, Uzair Hussain et al.
In briefExact probability laws for random inner products, including overlaps and Bargmann invariants
SummaryThis paper derives exact probability distributions for inner products of random matrices and random quantum states, such as overlaps, expectation values, and cyclic Bargmann invariants. The authors attribute these laws to two mechanisms: the diagonal of an induced random state is Dirichlet distributed, and expectation values of random pure states lie on a numerical shadow of an elliptical disk. The paper gives exact densities and limit theorems for several cases, including the overlap of random qubits, the Bargmann invariant of three Haar-random qubit states, and a Markov chain description for cycles of arbitrary length.
In briefPhoton production at Kepler escape threshold: an exact photon count for a Newtonian parabolic orbit, with radiation treated fully relativistically.
SummaryThe authors obtain a closed-form total photon count for a prescribed Newtonian Kepler parabola, treating its radiation fully relativistically. They also give closed expressions for the angularly resolved photon spectrum and elementary expressions for the total radiated energy and momenta. At large maximum rapidity the photon number grows roughly linearly while the energy grows exponentially, so the radiation mainly hardens; for slow motion, a nearby ellipse emits fewer photons but more energy and angular momentum per orbit.
In briefHigher-order disorder correlations shape reflected phonon counting statistics
SummaryThe paper studies how structural correlations beyond the power spectrum affect phonon counting in a one-dimensional acoustic stack. An integer-thickness construction cancels the leading backscattering term, so the finite-chain reflection depends on endpoint innovations. The authors derive a limiting normalized second moment for symmetric independent innovations and show that two ensembles with identical two-point correlations can give counting variances on opposite sides of the Poisson value.
In briefComplexity of Level-Synchronized Tree Automata for Checking Quantum Circuits
SummaryThis paper studies level-synchronized tree automata (LSTAs), which represent sets of quantum states for verifying quantum circuits. It examines the complexity of their decision problems and how their representation size changes under circuit operations. The authors prove that nonemptiness for acyclic LSTAs is NP-complete and their language inclusion is Π₂ᵖ-complete, while general language inclusion is EXPSPACE-complete. They also show that individual quantum gates cause inherent quadratic growth in representation size.
Michael Blondin, Samy Chady Khoumsi-Kasmi, Guillermo A. P\'erez et al.
In briefSuper Howe Duality and Rigidity of Hybrid Fourier Transforms
SummaryThis paper characterizes the hybrid Fourier transform on the Schwartz–Grassmann space by operator intertwining relations. Using bosonic Howe decomposition and fermionic Lefschetz decomposition, it describes the transform's action on both tensor factors. It shows that covariance under quadratic operators determines the transform, and makes it unitary after a normalization change. The authors also compute unitary conjugation formulas for a Hubbard–Holstein Hamiltonian in a hybrid continuous- and discrete-variable system.
In briefFast, high-fidelity atom transport in optical tweezers that preserves low motional energy
SummaryThis paper studies rapid transport of a single rubidium-87 atom between optical-tweezer sites, a step needed for reconfigurable neutral-atom processors. The authors use a basis-parameterized GRAPE pulse-optimization framework that tunes trajectory and trap-depth parameters. A 12.6 µm transfer completed in 30.5 µs reaches a ground-state infidelity of 2.41×10⁻⁷, and robust optimization under trap-depth noise is also reported.
Wen-hao Wang, Jian-gong Hu, Guang-ming Huang et al.
In briefUsing a Large Language Model to Guide Control of an Acousto-Optic Tweezer Array
SummaryThis paper experimentally tests a general-purpose large language model as a human-in-the-loop strategy layer for controlling a neutral-atom tweezer platform. Based on experimental feedback, the model switched from a multiplicative row-column correction to a drift-corrected local response-matrix method when separable feedback stalled. For a 10×10 crossed-acousto-optic-deflector array, the workflow reduced the Gaussian-peak coefficient of variation from 20.30% to 1.57% over 30 candidate-update rounds.
In briefChiral Floquet selection of an algebraic Rydberg bound state in the continuum
SummaryThis paper studies a Hermitian Rydberg spin waveguide coupled to a four-site plaquette. A winding drive phase combining rotation and time translation forbids propagating guide channels in one symmetry sector. The resulting eigenstate stays embedded in the continuum of other sectors and has an inverse-cube waveguide amplitude from direct coupling and long-range propagation.
In briefRoom-temperature optical readout of aqueous Cu(II) spin coherence via symmetry-breaking chelation
SummaryThe paper addresses the difficulty of optically reading out molecular electron spins in water, where Cu(II) previously needed about 1 M concentrations. Chelating Cu(II) with EDTA breaks symmetry, boosting absorption and magnetic circular dichroism by 7.3- and 5.6-fold and enabling spin readout down to 100 μM. Histidine extends the apparent dephasing time T2* from about 0.54 ns to about 0.8 ns in a concentration-dependent way, while glycine has no measurable effect.
In briefWhere to look for deviations from quantum mechanics
SummaryThis paper argues that measuring the lifetime and decay law of metastable helium is a promising way to detect deviations from quantum mechanics. The authors analyze the decay of a metastable state under a quartic deformation of quantum mechanics. They find that the absolute change in mean lifetime can be significant even when the modification is small. In the Wigner–Weisskopf approximation, deviations from exponential decay in the modified theory can appear on time scales comparable to the lifetime.
In briefEffects of Local and Correlated Pauli Noise on a Quantum Teleportation Circuit
SummaryThis paper analytically studies how the location and whether Pauli errors are local or correlated affect a three-qubit coherent quantum teleportation circuit. Independent local channels and a fully correlated two-qubit channel are inserted in six configurations, and expressions for the effective channel on Bob's qubit and for average and state-resolved fidelities are derived. The six configurations form three pairs that are equivalent for every input state, and the error response depends on the error statistics, Pauli axis, and position in the protocol.
L. Anjos, Jose Alfredo de Leon, R. S. Sarthour et al.
In briefMeasuring low-field J-coupling spectra with a diamond nitrogen-vacancy NMR spectrometer
SummaryThis paper reports homonuclear and heteronuclear J-coupling spectroscopy using a permanent-magnet NV-diamond NMR spectrometer at a proton Larmor frequency of about 890 kHz (bias field about 21 mT). The authors apply SyncE and SEDOR sequences to sample volumes near 50 pL, measuring 1J_CH couplings in methanol-13C and separating species in a methanol-13C/acetonitrile-2-13C mixture. They also acquire a homonuclear J-coupling spectrum of natural-abundance propylene carbonate.
Stephen J. DeVience, John W. Blanchard, Camille G. McDonnell et al.
In briefAdiabatic Z-phase gate for neutral atoms using Förster-enhanced Rydberg dressing
SummaryThis paper studies an adiabatic controlled-Z gate for neutral atoms, where dipole-dipole coupling between nearly degenerate Rydberg pair states strengthens interactions between dressed ground states. The authors identify an operating range enhanced by this Förster coupling in which the conditional phase builds up with small transient Rydberg population. The selected gate achieves high Bell-state fidelity and corresponds to experimentally relevant parameters for a rubidium Förster channel. Error estimates indicate that spectator-atom-induced error is smaller than the error from finite Rydberg lifetime.
SummaryThe paper shows that a certain bipartite language admits a quantum communication protocol with poly-logarithmic cost, while its Merlin-Arthur communication complexity is polynomial. The abstract states only this result without further detail.
WhySeparates quantum and Merlin-Arthur communication classes, improving known bounds with a rigorous result, though impact stays within a narrow subfield.
