July 1, 2026

Simulation of Two-qubit Gate Variability and Fidelity of Spin Qubits Built on Nanosheet Technology

Silicon spin qubits are promising for large-scale quantum-computer integration because they can fully leverage the well-developed semiconductor infrastructure. However, the low fidelity of two-qubit entanglement gates remains a key barrier to large-scale integrations. Recent simulations of silicon spin-qubit two-qubit gates have been performed on silicon-on-insulator (SOI) p...

Efficient entanglement of three remote single-atom quantum-network nodes

Entanglement distributed over a set of individually addressable qubit nodes is the enabling resource for a plethora of applications ranging from tests of quantum physics to secure and modular quantum information networks. Entanglement between two memory qubits has been realized on various platforms, but extension to more nodes remains rare and formidably challenging. The pri...

Spatially Coupled MacKay-Neal/Hsu-Anastasopoulos CSS Codes Achieve the Quantum-Erasure Hashing Bound by Seeded BP Decoding

In classical sparse-graph coding, spatial coupling is a mechanism by which belief-propagation (BP) decoding attains the maximum-a-posteriori (MAP) or area-threshold performance of the uncoupled system. Since MacKay-Neal/Hsu-Anastasopoulos (MN/HA) punctured sparse ensembles achieve capacity under MAP decoding, it is natural to ask whether spatially coupled MN/HA-type Calderba...

State-dependent Gaussian gate set using an optical tweezer for trapped ions

We demonstrate a state-dependent Gaussian gate set on the motional modes of trapped ^(40)Ca^+ ions, realized with an optical tweezer. Dynamic control of the tweezer intensity and position enables local displacement, squeezing, phase-space rotation, and beamsplitter operations, constituting a complete gate set. By varying the tweezer position relative to the ion, we show...

Lazy-Move Compilation for Neutral-Atom Quantum Computers via a Buffer-Relay Fabric

Neutral atom quantum computing offers strong scalability and flexible qubit connectivity, but most existing compilation flows rely on reconfigurable atom arrays that physically shuttle qubit atoms during execution. Although this approach improves connectivity, it also introduces handoff errors, motional heating, and atom-loss risks that can degrade overall fidelity. We prese...

Correlation is magic in electronic structure Hamiltonians

The gate and qubit requirements of quantum computations of electronic structure have been extensively studied. However, the quantum resources present in electronic ground states, as measured by entanglement and magic, remain less well understood. We study the relationship between correlation in electronic structure Hamiltonians and magic as measured by the 2-stabilizer Renyi...

Context-Verified, Error-Budget-Aware Decomposition Selection for Toffoli Networks

Two-qubit-gate error dominates the failure budget of near-term quantum circuits, so the decomposition chosen for each Toffoli (CCX) gate should minimize hardware two-qubit infidelity, not gate count. The cheapest decompositions - relative-phase and approximate Toffolis - are only correct in context: their residual phase or bounded error must be cancelled or absorbed downstre...

Hadronic exceptional points

Exceptional points, where eigenvalues and eigenvectors coalesce, are a defining feature of non-Hermitian systems and have been extensively observed in photonic, atomic, and condensed matter systems. However, they have received little attention in quantum chromodynamics (QCD), which is the fundamental theory of quarks, gluons, and hadrons. We propose that imaginary magnetic f...

Beyond the Expressivity-Trainability Paradox: A Dynamical Lie Algebra Perspective on Navigating Barren Plateaus in Quantum Machine Learning

As Quantum Machine Learning (QML) transitions toward practical implementation, the field faces a critical architectural bottleneck that challenges the fundamental assumptions of classical statistical learning theory. In classical deep learning, increasing model capacity typically risks overfitting. However, this study advances a counter-intuitive paradigm: unstructured conte...

Machine Learning based Optimization of CV-QKD Under Practical Constraints

Practical hardware limitations, including finite transmitter and receiver filter lengths as well as the finite resolution of digital-to-analog and analog-to-digital converters, lead to mode mismatch and degrade the performance of continuous-variable quantum key distribution systems. To address this, we develop a machine learning-based end-to-end optimization framework that j...

A Quantum-Classical Surrogate Model for the Collision Operator of the Lattice Boltzmann Method

We introduce a hybrid approach utilising a quantum machine learning surrogate model to approximate the non-linear collision dynamics of the LBM. It effectively offloads the non-unitary operations that challenge pure quantum solvers. The expressivity of the surrogate is built on the ability of parameterised quantum circuits to implement partial Fourier series, with data re-up...

Full-Wave Green's-Function Modeling of Collective Single-Photon Emission in Non-Markovian Open-System QED with Finite-Bandwidth Compensation of Dispersive Interactions

This work presents a full-wave Green's function framework for modeling collective and coherent single-photon emission from multiple quantum emitters embedded in complex electromagnetic structures. Starting from a transverse modal completeness relation of modified Langevin noise formalism, we derive a closed set of coupled equations for population dynamics and frequency-resol...

Automatic quantum function parallelization and memory management in Qrisp

Automated optimization of quantum programs has gathered significant attention amidst the recent advances of hardware manufacturers. In this work we introduce a novel data-structure for representing quantum programs called permeability DAG, which captures several useful properties of quantum programs across multiple levels of abstraction. Operating on this representation faci...

Signatures of the circular Unruh effect in electric and magnetic dipole transitions of multilevel atoms

The circular Unruh effect is the excitation of a detector moving along a planar circular trajectory within an electromagnetic vacuum. We demonstrate that the magnetic dipole transitions in an atom, acting as the detector, dominate the electric dipole transitions. Our analysis of both free-space and cavity schemes shows that the sensitivity to the circular Unruh effect can be...

Wave-particle duality as an uncertainty relation for the average confidence width

We introduce the average confidence width Δ_a x=∫_0^1 Δ_c x (θ_x) d θ_x: the confidence width Δ_c x(θ_x) -- the smallest position interval carrying a fraction θ_x of the probability -- averaged over all levels. It is the first moment of the decreasing rearrangement of |ψ|^2, an L^1 mean-absolute-deviation measure of localization, so the product $Δ_{a} x\,Δ_{a} p...

StarkWare Unveils Quantum-Safe Roadmap for Starknet

Europe Launches Quantum Skills Academy to Expand Workforce Development

Pasqal and Crédit Agricole CIB Deepen Partnership on Quantum Finance Applications

D-Wave to Receive $1.5 Million Grant through NSF Project

Quantum Information as a New Lens for Precision Neutrino Physics

We present a quantum-information-theoretic study of three-flavor neutrino oscillations in long-baseline experiments by mapping flavor states to qubit-like representations and quantifying quantum correlations through total concurrence. The local minima of this entanglement measure identify energy regions where the flavor state is closest to separability, enabling cleaner extr...

The contact temperature of arbitrary quantum states

An intuitive scheme to assign a temperature to an arbitrary state of a quantum system is to investigate the heat flow resulting from the coupling to a thermometer. We introduce a simple model of a universal thermometer with the following property. When it is prepared in a Gibbs equilibrium state at inverse temperature β∈R and brought into thermal contact with a s...

An efficient Pauli decomposition algorithm for structured matrices

Decomposing classical matrices into linear combinations of Pauli strings is a major bottleneck for end-to-end implementations of near-term quantum algorithms. In this work, we consider a promise version of this Pauli decomposition problem in which the matrix is guaranteed to have support on only k = poly(n) Pauli strings and is given through classical sparse query...

Resonant and collective modification of London dispersion interactions under vibrational strong coupling

Experiments have shown that, by tuning a microcavity to resonance with a vibrational mode of the molecules contained within it, one can modify chemical properties, such as reaction rates. This gives rise to the exciting prospect of steering chemical reactivity, just by placing a pair of carefully spaced mirrors around the reaction mixture. However, a decade after the first d...

Certifying quantum states without independence assumptions

Standard quantum verification and certification protocols often assume that experimental sources emit independent and identically distributed (i.i.d.) states. In realistic scenarios, however, temporal drift, memory effects, feedback, and correlated noise can violate this assumption, causing standard analyses to underestimate uncertainty and overestimate device performance. H...

Electrons on Helium and Entangled Quantum Sensors for Particle Physics

Quantum sensors that harness quantum coherence and entanglement are emerging as powerful tools in many fields, including particle physics, promising unprecedented sensitivity beyond classical detection methods. At the same time, electrons trapped on the surface of liquid helium have emerged as a promising quantum computing, and possibly sensing, platform owing to a nearly im...

Giant perpendicular Edelstein polarization in 2D compensated magnets via bichromatic Floquet driving

While unconventional p-wave magnets can generate nonrelativistic Edelstein polarizations, spin-group symmetries strictly forbid these responses in unconventional magnets with higher-order harmonics, such as d-wave altermagnets. Here, we demonstrate that combining Rashba spin-orbit coupling with bichromatic Floquet driving activates giant perpendicular Edelstein polarizat...

Generating uniform quantum state ensembles with continuous measurement

We investigate the generation of uniform quantum state ensembles via continuous measurement. Using the SU(d) Bloch representation, we derive the associated Langevin and Fokker-Planck equations and identify geometric conditions under which homogeneous monitoring causes global convergence to the uniform pure-state ensemble. We then extend the analysis to mixed states, showin...

Correlation-enhanced metrology from scrambling dynamics in a solid-state spin system

Quantum information scrambling, the dispersal of local information into many-body degrees of freedom, provides a powerful mechanism for generating large-scale correlations and entanglement essential for quantum-enhanced metrology. However, experimentally verifying such quantum-enhanced metrology remains a demanding task. Here, we correlate thousands of spins by engineering c...

Improving Perturbation Theory with the Sum-of-squares II: Large Density-Density Terms

In Ref. 1, a method was given for self-consistently generating sum-of-squares decompositions of quartic fermionic Hamiltonians. Perturbation theory was used to generate a useful choice of cubic operators in this sum-of-squares. On a range of model problems, this method, which is only a fragment of degree-six sum-of-squares, was able to outperform the full degree-four sum-of-...

Plasmon-Enabled High-Precision Single Molecule Localization Microscopy over an Extended Field of View

We propose PIFLUX, a single-molecule localization scheme combining deep-subwavelength plasmonic illumination with widefield detection. Interference between counter-propagating gap plasmons and a normally incident optical field generates an illumination pattern whose position can be tuned through the plasmon phase while preserving its spatial period. A Cramér-Rao analysis sho...

Distributed Property Testing with (Quantum) Carrier Pigeons: Tight Bounds on State Certification

Recently, Doosti et al. introduced the problem of distributed quantum state verification, where m distributed nodes are given a copy of an unknown state ρ, and can send limited one way communication to a central node, who has a complete description of a known state σ. They ask how many distributed nodes m are required, before the central node can succeed at distingui...

Entangled photons from para-positronium decay: Do coincidences from scattered photons imply a Bell state?

Electron and positron can form a meta-stable bound state called positronium that decays via pair annihilation. We show how polarization-dependent Compton scattering can be used to verify that the two annihilation photons in the spin-zero case (para-positronium) are emitted in a maximally entangled Bell state. Our theoretical approach based on two-photon density matrices conn...

Holographic Krylov Complexity with Lifshitz Scaling and Hyperscaling Violation

Following the holographic proposal that identifies the growth rate of Krylov complexity with the proper radial momentum of an infalling massive probe, we study Krylov complexity in Lifshitz and hyperscaling-violating backgrounds. For pure Lifshitz geometries, we derive exact analytic solutions and obtain quadratic complexity growth for all values of the dynamical exponent. F...

Boosted Optomechanics with a Fluid of Nonlinear Polaritons

Merging optomechanics and polaritonics opens stimulating perspectives like the giant enhancement of optomechanical interaction and the enrichment of optomechanics with effective nonlinear photons. The experimental implementation of these concepts has however remained elusive. Here we report on the resonant optical control of polaritonic optomechanical resonators constituted...

A Quantum Collocation Approach to One-Dimensional Boundary Value Problems with Coherent Amplitude Amplification

We propose a quantum collocation framework for approximating solutions of one-dimensional linear and nonlinear boundary value problems. The method formulates the search for admissible solutions as a residual-based quantum search over a discretized ansatz space, where candidate solutions are evaluated through residual conditions imposed at collocation points. A residual-thres...

Relativistic Gravity-Induced Entanglement via Frame Dragging

Gravity-induced entanglement has been proposed as a method for testing the non-classical nature of gravity via tabletop experiments. While most existing proposals are restricted to the Newtonian limit, the frame dragging effect offers access to genuinely post-Newtonian features of the gravitational interaction and remains comparatively less explored. Here, we study gravity-i...

Suppressing Parametric Instabilities in Driven Bosonic Lattices through Multi-tone Control

Periodically driven quantum systems offer remarkable flexibility in tailoring effective Hamiltonians and synthetic band structures. However, such driving also induces heating and dynamical instabilities that limit the coherence and lifetime of many-body states. Here, we demonstrate that these instabilities can be suppressed by employing multi-tone driving schemes. Using a Bo...

Nonequilibrium Casimir-Polder Force: Magnus-like Effect

The motion of a particle in vacuum near macroscopic bodies gives rise to a Magnus-like contribution to the nonequilibrium Casimir-Polder force. This effect originates from the interplay between particle dynamics and material-modified electromagnetic quantum fluctuations, inducing in the particle a direction-dependent angular momentum coupled to the electromagnetic field spin...

Memory-Scalable and Hardware-Adaptive Matrix-Free Quantum Simulation

The core step in quantum simulations is typically matrix vector multiplication φ= Hmatψ. Executing this step is limited by memory requirement to store the Hamiltonian. We present a memory-scalable, hardware-adaptive matrix-free framework for applying large operators on vectors without materializing the full matrix on a single accelerator. The operator is represented thro...

Topological zero-reflection points in multi-terminal quantum wire junctions

We study scattering in noninteracting multi-terminal quantum wire junctions and show that junctions with dihedral symmetry can exhibit exact zero-reflection points for N ≥4 terminals. By analyzing the scattering matrix, we identify these reflectionless points in the (E,t') parameter space, where E is the incident particle energy and t' is the junction hopping ampl...

A logarithmic phase singularity at the heart of Landau-Zener transitions

Three ingredients of the elementary Landau-Zener problem determine the familiar expression a_(LZ)≡exp[-π/(2ε)] for the asymptotic value of the probability amplitude for remaining in the initial level: (i) A wave whose phase is determined by the product of a contour integral over a simple pole at the origin of the complex plane and the inverse of twice the...

Nonlinear Schrödinger equations: Symmetries, superposition, and classicality from a Bohmian perspective

Interference is commonly regarded as the most direct manifestation of the superposition principle. This association is natural for the linear Schrödinger equation, where coherent alternatives combine at the level of probability amplitudes. However, the situation becomes less transparent when nonlinear couplings are present, or when the field is only partially coherent. In th...

Temporal-Plane Carroll--Schrödinger Dynamics and Vortex Sectors in (2,2) Klein Space

Motivated by the temporal dynamics identified in the (1+1) Carroll-Schrödinger theory, we derive a post-Carrollian Schrödinger dynamics in flat Klein space with signature (2,2). Starting from the tachyonic Klein-Gordon equation in double-polar coordinates and removing a spacelike carrier, the spatial radius behaves as an effective evolution parameter, whereas the tempora...

Spectral Multipartite Entanglement

We introduce a unified, computable measure of multipartite entanglement based on the spectral properties of an entanglement graph and its associated entanglement matrix. This framework quantifies quantum correlations among arbitrary subsystems and partitions of a composite system. We prove that the resulting spectral entanglement measure satisfies the fundamental requirement...

Programmable optical parametric amplifier synthesizer for cubic phase states and amplified Schrodinger cat states

We introduce a programmable optical parametric amplifier (OPA) synthesizer that, under a heralded photon-number-resolving framework, generates high-fidelity cubic phase states and amplifies Schrodinger cat states. By systematically exploring both the catalytic configuration, where the idler input and output contain the same number of photons (m=n), and non-catalytic config...

Non-Hermitian Rayleigh-Schrödinger-like Perturbation Theory at Exceptional Point

We develop a Rayleigh--Schrödinger-like perturbation theory for non-Hermitian quantum systems at an exceptional point of order N. Working in the Jordan basis of the unperturbed Hamiltonian and employing a Puiseux expansion of the perturbed eigenvalues and eigenstates, we derive explicit recursion relations for the expansion coefficients. The corrections to the unperturbed...

Absorption capacity of separable noise: Bell-mixing thresholds on separability and teleportation

We study Bell-mixing lines ρ_λ=λΦ^+ +(1-λ)σ, where Φ^+ is a fixed Bell reference and σ is a separable two-qubit noise state. Along this line there are two operational crossings: the state becomes entangled, and it reaches quantum teleportation advantage over classical strategies. We package these crossings as capacities of the noise state. The entanglement absorption c...

Mapping photon-number regimes in single-emitter lasers

Cavity quantum electrodynamics (cQED) architectures are known to produce traditional laser signatures from a coherently driven single quantum emitter. In this paper, we present a numerical analysis of an open quantum system consisting of an incoherently pumped three-level emitter strongly coupled to a single cavity mode. In particular, we focus on three cavity photon-number...

Unresolved-Sideband Optomechanics with Hexagonal Boron Nitride: Induced Transparency, Gain, and Frequency Combs

Optomechanically induced transparency (OMIT) is usually modeled and studied in the resolved-sideband regime, but many compact microcavity platforms operate in the unresolved-sideband limit (κ≫Ω_m). Here we investigate OMIT in this regime using a tunable fiber-based Fabry-Perot microcavity coupled to a suspended hexagonal boron nitride (hBN) drum resonator in a membrane-...

Copernic Space and Intrana Partner to Secure Space Assets Against Looming Quantum Threat

Quantum X Labs Appoints Dr. Ira Wolfson as Quantum Researcher

The Quantum Kid turns 1! (and Kai turns 10)