June 8, 2026

Collective emission of subwavelengths atom-like emitter arrays in the presence of inhomogeneous broadening

Quantum metasurfaces comprised of subwavelength atomic arrays emerged as a promising platform for enhanced atom-photon interaction. However, realizing such a system with solid-state emitters has been considered impractical due to strong inhomogeneous broadening, which was expected to suppress the photon-mediated interactions that underpin collective emission. Here we report...

Tomography of quantum states with bounded extent

We give a general framework for tomography of states that have bounded-extent with respect to a structured class of states. Let textsfC be a family of n-qubit states such that: (i) textsfC is succinctly representable and (ii) there is a weak agnostic learner of textsfC. We give a tomography protocol for an unknown state |ψ⟩ that is promised to ad...

Coherent versus stochastic error injection on a repetition-code logical qubit in superconducting hardware

The performance of quantum error correction (QEC) codes is limited by the underlying physical noise. Theoretical studies show that coherent and stochastic noise have different effects when performing QEC with either surface or repetition codes. We use the bitflip repetition code, realized in a transmon quantum processor, as a testbed to experimentally study the impact of inj...

Suppression of Quasiparticle Poisoning to 10^(-11) Levels in Superconducting Qubits via Infrared Shielding

Quasiparticle poisoning bottlenecks superconducting qubits, limiting coherence and the scalability of quantum processors. In this work, we systematically investigate quasiparticle poisoning in superconducting qubits under three infrared (IR) shielding configurations, ranging from a dedicated multi-layer design to a simplified implementation. By measuring quasiparticle-induce...

Vacuum fluctuation induced quantum resource harvesting in triple-layer graphene

We examine the non-Markovian dynamics and the generation of quantum coherence and entanglement within a triple-layer graphene (TLG) system embedded in a planar microcavity. Using time-dependent perturbation theory, we derive an exact analytic solution for the system and demonstrate how the confined electromagnetic field mediates quantum correlations between the graphene laye...

Improved Cryogenic Photodiode Optical Biasing for Low-Noise and Low-Jitter Superconducting Nanowire Single-Photon Detectors

We experimentally demonstrate an improved optical biasing scheme for superconducting nanowire single-photon detectors (SNSPDs), which employs a cryogenic InGaAs-InP photodiode (PD) as a local bias source. It is found that, under illumination from a stable external light source, this PD generates a stable photocurrent in a cryogenic environment (~2.3 K), with fluctuations in...

Complex-gauge control of anomalous Floquet corner responses in a non-Hermitian physical-synthetic photonic lattice

We propose a non-Hermitian Floquet photonic lattice formed by a physical resonator coordinate and a synthetic frequency coordinate. A two-step modulation protocol realizes a chiral walk in this physical-synthetic plane, with a real synthetic flux controlling loop interference and imaginary gauge fields controlling non-reciprocal envelopes. We show that anomalous corner pairs...

Solution of the Equation-of-Motion Phonon Method eigenvalue problems on the D-Wave quantum annealer

The solution of large-scale eigenvalue problems is crucial in nuclear many-body theory, where Hamiltonian matrices often reach extremely large dimensions. Quantum computing opens new perspectives for addressing such demanding problems. Although the Quantum Phase Estimation algorithm offers, in principle, a systematic route to matrix diagonalization, its practical deployment...

Driving Exchange Interaction in Spin Qubits with Quasi-Zero Pulses

The implementation of high-fidelity quantum gates for spin qubits requires accurate control of exchange interactions between electrons confined in quantum dots, but pulse distortions can limit this control accuracy. Although linear-dynamical distortions can be compensated for by appropriately convolving the control signal, determining the necessary convolution requires detai...

Measurement circuit ansatz: Naimark versus quantum neural-network measurements

In this work, we present constructions of quantum circuits to implement general measurements on quantum hardware. Firstly, we investigate a quantum circuit ansatz by following the Naimark extension with a universal set of gates, such as controlled-NOT and single-qubit gates; we call it a Naimark quantum measurement. We present a circuit ansatz framed by the Naimark extension...

Towards Implementable Quantum Divide and Conquer: A TSP Solver with Improved Exponential Base over Held-Karp

The traveling salesman problem (TSP) is a significant classical NP-hard combinatorial optimization problem. In this work, we demonstrate that combining classical dynamic programming with quantum search can yield an achievable quantum advantage for TSP on the basis of excellent work by the authors of~\cite{ambainis2019quantum}. We design the quantum divide and conquer strateg...

Continuous-time quantum control across an exponentially small bottleneck in a frustrated Ising ring model

Continuous-time Quantum Annealing (QA) is a strategy for preparing the ground state of nontrivial many-body systems. In its standard form, the dynamics is generated by a time-dependent interpolation between a simple driving Hamiltonian and the target problem Hamiltonian, usually implemented through a linear schedule. This approach faces the crucial bottleneck of small spectr...

Projector Quantum Variational Ansatz

Quantum computing offers several algorithms to compute the ground state of a problem Hamiltonian. The most desirable algorithms belong to the Fault Tolerant QuantumComputing (FTQC) regime, such as quantum algorithms with repetitive structure like Quantum Phase Estimation (QPE) and Quantum Signal Processing (QSP). However, in the Noisy In-termediate Scale Quantum (NISQ) regim...

Machine-Learning Optimization and Characterization of a High-Optical-Depth Two-Color Nanofiber Trap

Optical nanofibers provide a way of coupling quantum information in cold atoms across large distances, however, this coupling requires atoms to reside close to the nanofiber surface. Atoms can be trapped close to the surface using a two-color dipole trap. Here we present our experimental realization of a two-color dipole trap. We optimize the number of trapped atoms using a...

Computational Superiority of Non-Markovian Kerr Feedback in Continuous-Variable Quantum Reservoir Computing

A linear optical medium can delay, mix, and superpose light, but never make two pulses multiply: multiplication is nonlinear, and a linear system has no such operation. This roots a sharp limit on continuous-variable quantum reservoir computers (QRCs) built from Gaussian optics. Within the reservoir they cannot form genuine products of the input at different past times, the...

Unified Framework for Functional Theories of Quantum Systems

We introduce and study a unified framework for density-functional theory and its variants for quantum systems on finite-dimensional Hilbert spaces. These theories seek to reduce the complexity inherent in the many-body quantum problem by describing ground states through reduced variables. The central ingredients of our unified framework are a generalized choice of basic obse...

Light-tunable quantum metric non-linear Hall response in Berry dipole semimetals

We investigate the effect of light on quantum metric-mediated intrinsic nonlinear Hall conductivity in Berry dipole semimetals. We discover that light induces a tunable asymmetry in the off-diagonal part of the quantum metric, which is manifested by an asymmetry in the quantum metric dipole. We show that the nonlinear response can be tuned directly by the light amplitude. In...

Higher-order Symmetric Quantum Mpemba Effect in Fragmented Systems

A quantum system can restore a broken symmetry faster the more strongly it initially breaks it, an anomaly known as the quantum Mpemba effect. Whether this effect survives once conservation laws fragment the Hilbert space into exponentially many disconnected Krylov sectors has remained open. We address this question for circuits and Hamiltonians with simultaneous charge and...

Why Quantum Computing Companies Are Turning to SPACs

Quantinuum and Mitsubishi Electric Sign Quantum Computing MOU

UK Risks Repeating Semiconductor and AI Mistakes Unless Government Acts Now on Quantum, Warns Cross-Party Parliamentary Group

Quantum correlations in QBism's reconstruction program

QBism recasts quantum theory as a normative framework for an agent's probability assignments, with the Born rule taking the form of a consistency condition known as the Urgleichung. Motivated by this perspective, qplex theories provide a broader class of probabilistic models in which the sets of valid states and measurements are constrained by QBist-inspired geometric condit...

Topologically Enforced Lifshitz Multicriticality in One Dimension

Recent advances have revealed that topology can further enrich the universality classes of quantum phase transitions, thereby extending beyond the traditional paradigms of statistical and condensed matter physics. However, multicriticality between topologically distinct quantum critical lines remains insufficiently explored. In this Letter, we systematically construct and in...

Ferroelectrical Switching as a Probe of Quantum Damping in Magnetic Spin Systems

While damped spin dynamics is important for the understanding of magnetic materials, clear signatures of \emph{quantum corrections} to the Gilbert damping mechanism remain elusive. We propose a route to distinguish quantum and classical Gilbert spin damping using ferroelectric control of a magnetic dimer. Ab initio calculations for dimers on ferroelectric substrates show tha...

Tests of constructor theory

Constructor theory is a proposal to extend quantum information theory beyond both quantum theory and computation, to cover more general machines than programmable computers -- called constructors. It consists of newly conjectured physical principles that can be expressed as constraints on what tasks are possible, what are impossible, and why. These principles also determine...

Performance analysis of classical adiabatic annealing on Ising machines

Ising machines are a promising approach to solve combinatorial optimization problems. They map these problems onto the Ising model and search for low-energy configurations. However, navigating the rugged energy landscapes of these systems remains difficult. To improve this navigation, classical adiabatic annealing has been proposed in the literature as a heuristic optimizati...

Proof that the Klein-Gordon type equation with alpha attractor potential has no Liouvillian solution or as a composition of special functions

This study investigates the analytical solvability of the Klein-Gordon and Duffin-Kemmer-Petiau (DKP) equations for a scalar particle interacting with a transcendental α-attractor-type potential, V(x) = V_0 e^(a tanh(bx)). We first address the problem of integrability within the framework of Picard-Vessiot theory. By analyzing the differential field extensions associate...

QBugLM: An Agentic Benchmarking Framework for LLM-based Quantum Software Debugging

Quantum software bugs often yield silent, incorrect outputs rather than explicit errors, making them particularly difficult to detect and repair with conventional techniques. Although large language models (LLMs) have shown strong performance on classical software engineering tasks, their ability to debug quantum code remains largely unexplored. To bridge this gap, we propos...

Quantum critical properties of non-Hermitian XY models with magnetic field

The characterization of the quantum critical properties of genuine non-Hermitian many-body systems remains ambiguous as neither the state considered nor the definition of expectation values is unique. In this work, we investigate the quantum critical properties of two models of non-Hermitian XY spin chains with magnetic field. Using exact solutions, we systematically investi...

Elucidating the Control of Circular Dichroism in Ion Yield via Chirped Pulses with Purposeful Models

We theoretically investigate circular dichroism in the ion yield following 1+1+1 ionization of 3-methylcyclopentanone using femtosecond linearly chirped laser pulses, inspired by recent experiments by Das et al. [Phys. Chem. Chem. Phys. 27, 8043 (2025)]. To this end, we numerically solve the time-dependent Schrödinger equation and evaluate the total population in the Rydbe...

Long-range interactions assisted shortcuts to adiabaticity and battery charging in open quantum critical systems

In this work we show that long-range interactions can be significantly beneficial for implementing shortcuts to adiabaticity (STA) in many-body open quantum critical systems driven out of equilibrium, as well as for charging quantum batteries in the presence of dissipation. In sharp contrast to short range interactions where passage through criticality may demand STA control...

Experimental Demonstration of Free-Space Unidimensional Continuous-Variable Quantum Key Distribution Under High Detector Noise

Continuous-variable quantum key distribution (CV-QKD), which uses quadratures of the electromagnetic field, enables practical quantum communication using standard telecommunication technologies. Unidimensional CV-QKD (UD-CVQKD) simplifies the implementation by restricting modulation to a single quadrature. In this work, we experimentally demonstrate a free-space Gaussian-mod...

Asymmetry dynamics and nonequilibrium symmetry-breaking phase transitions

In classical settings, the Mpemba effect occurs when a hotter system cools faster than an initially colder one. In quantum systems, this effect can be reinterpreted exploiting the concept of symmetries, with the asymmetry of a subsystem playing the role of temperature. A quantum Mpemba effect arises when a more asymmetric state restores the symmetry faster than a less asymme...

Quantum correlations and coherence in a two-qubit anisotropic XY under magnetic field

We study thermal quantum correlations and coherence in Heisenberg XY model with anisotropic interactions under a uniform magnetic field $ B $. Using concurrence C, local quantum uncertainty (LQU), Bell-Clauser-Horne-Shimony-Holt (CHSH) nonlocality B, and coherence C_l as quantifiers, we analyze how magnetic anisotropy δ_m, coupling anisotropy δ_c, D...

Exact noise characterization of entanglement distribution in star networks

Multipartite entanglement forms the core of many networking applications. In the near-term future, it is expected that multipartite distribution will be achieved first through star topologies, making it important to understand the noise incurred during the distribution process. In such networks, elementary links are created stochastically and successful links must be stored...

Frequency Detuning and Interference-Induced Bohmian Chaos in a Two-Dimensional Anisotropic Harmonic Oscillator

We investigate the emergence of chaotic Bohmian trajectories in a three-mode superposition of the ground and first excited states of a two-dimensional anisotropic harmonic oscillator. The analysis focuses on the interference-induced phase structure of the wavefunction, which determines the Bohmian velocity field through its phase gradient. We show that the spatial extent of...

Regular and chaotic dynamics of nonlinear optomechanical systems controlled by modulated light

The nonlinear dynamics of a mechanical resonator in an optomechanical system with linear, quadratic and cubic photon-vibration interactions (with respect to mechanical displacements) in a modulated driving field under conditions of adiabatic elimination of the optical field is studied. Based on the constructed bifurcation diagrams of the mechanical coordinate and the largest...

Nonreciprocal optomechanical entanglement in an asymmetric Fabry-Perot cavity

Nonreciprocal transmission (classical nonreciprocity) in optomechanical systems based on asymmetric Fabry-Perot (F-P) cavities has been theoretically proposed and experimentally demonstrated. However, nonreciprocal quantum effects, particularly nonreciprocal quantum entanglement, remain unexplored in such systems. Here, we propose to generate nonreciprocal optomechanical ent...

Cyclic ladder operators and hidden Weyl-Heisenberg structure in a Floquet system

Ladder operators, found in the quantum harmonic oscillator and other quantized systems, provide an elegant approach to solving or understanding otherwise intricate physics problems. In this Letter, we discuss cyclic ladder operators in both Hermitian and non-Hermitian systems with a finite Hilbert space, with the highest (lowest) level directly descending (ascending) to the...

Bures geodesics for non-faithful states and quantum speed limit

The quantum speed limit establishes a bound on the minimal time required for a quantum system to evolve from a given initial state to a final state. When the mean energy variance is fixed this limitation is captured by the Mandelstam--Tamm bound. The fastest quantum evolution saturating this bound follows a geodesic arc connecting the two states. Such geodesics in the manifo...

Non-Hermitian Crystalline Braid Topology from Hermitian Projection: A Zero-Mode Resonance Mechanism

Non-Hermitian topological phases are usually engineered through gain, loss, asymmetric couplings, or explicit environmental channels. Here we show that non-Hermitian crystalline braid topology can instead emerge from projection alone, starting from a fully Hermitian and topologically trivial parent lattice. The mechanism is zero-mode-resonant projection. When the eliminated...

Collective decay of interacting bosons

We study a bosonic analog of the paradigmatic Dicke model of superradiance, comprising interacting bosonic modes subject to fully symmetric collective decay. Depending on the interaction strength, we uncover qualitatively distinct regimes of emission. For strong interactions, the emission closely resembles Dicke superradiance, with perturbative corrections arising from the p...

Sensing ac fields with quantum many-body scars

Quantum many-body scars (MBS) exhibit weak ergodicity breaking and long-lived coherent dynamics within an otherwise thermal spectrum. We investigate their metrological properties using the quantum Fisher information (QFI), focusing on estimating the amplitude of a weak AC field in the PXP model. We show that the approximately uniform energy spacing of the scar tower enables...

Quantum-stabilized patterns in a vector Hopfield network

We introduce the quantum vector Hopfield network, in which patterns are formed by orientations of quantum vector spins; quantum dynamics arise intrinsically from the non-commutativity of the spin operators. We derive the equations of state and the phase diagrams for this network as well as its classical counterpart. We find that quantum fluctuations, surprisingly, stabilize...

Fun with Graph States: Nonlocal Bell Pairs and the Arf Invariant

We study inner products and partial amplitudes of graph states--a commonly employed class of quantum states, which are specified by graphs. We find that the magnitudes of these quantities are simply related to the rank of the adjacency matrix of the graph over F_2 while the phase is determined by the Arf invariant of its quadratic refinement. These facts motivate a nonlocal...

Enhancement of charge correlations and real-space topological marker on an interacting non-Hermitian Su-Schrieffer-Heeger model

We investigate the interacting non-Hermitian Su-Schrieffer-Heeger (SSH) model, focusing on the interplay between topology and charge ordering. Using a real-space topological marker, charge correlations, and the complex many-body spectrum, we map out the phase diagram under periodic and open boundary conditions. We show that the topological marker remains a robust diagnostic...

SEALSQ Broadens Quantum Computing and Post-Quantum Security Strategy

Scientists Identify the Origin of Noise in Spin Qubit Quantum Processors

Quantum X Labs Adds Oren Raz to Scientific Advisory Board