September 9, 2026

Dual-Trigger of Series Nanowire Detector for Event-Based Photon Number AssignmentTier 3

Photon-number-resolving (PNR) detectors are essential components of photonic quantum technologies. However, conventional single-channel edge-triggered readout struggles to resolve the photon number n in real time or to characterize how timing jitter depends on n. In this work, we use a dual-trigger method on a three-pixel series-connected superconducting nanowire single-...

Preparation of a Bell state in an analogue device hosting the transverse-field Ising modelTier 3

We propose a protocol for preparing the singlet Bell state in an analogue device implementing the transverse-field Ising model with ZZ interactions and local X and Z fields, which can be engineered within the superconducting platform, among others. This protocol is performed by direct control of the terms of the Hamiltonian alone. The method exploits the fact that the single...

First fault-tolerant quantum memory demonstration for a generalized superfast encodingTier 3

The Generalized Superfast Encoding (GSE) is a fermion-to-qubit mapping that has error-correcting/detecting properties. To this point, all demonstrations have been relegated to error-detection only, as no fault-tolerance under circuit-level noise has been observed. Here, we introduce an even-distance d constant stabilizer-weight GSE where each of N modes is assigned a d...

Resilience Beyond the Light Cone: Error-Detected Primitives for Practical Dynamic CircuitsTier 3

Dynamic circuits, which augment unitary operations with mid-circuit measurements and classical feedforward, can generate long-range entanglement in constant depth, enabling low-depth primitives ranging from nontrivial state preparation to many-qubit entangling gates. Escaping the light-cone constraints of unitary circuits, however, comes at a cost: these primitives typically...

Adaptive AI for Pulse-Level Quantum ControlTier 3

The Control Variational Quantum Eigensolver (ctrl-VQE) directly optimizes microwave pulses to enable faster and lower-error quantum-state preparation, but its continuous control landscape re- quires efficient search strategies. We demonstrate that a reinforcement-learning agent based on a deep Q learning network can autonomously discover high-performance pulse sequences usin...

Recovering Readout-Limited Fisher Information in Superconducting-Qubit Magnetometry with Squeezed MicrowavesTier 3

The performance of superconducting-qubit magnetometers depends not only on magnetic-field encoding during Ramsey interrogation, but also on how efficiently the encoded information is recovered during readout. Here we quantify how squeezed-microwave-assisted dispersive readout can recover magnetic-field information lost during qubit-state assignment. We develop an effective d...

Explicit block encodings of rate matrices for simulating polymerization kinetics on quantum computersTier 3

Predicting how molecular weight distribution and monomer sequence evolve during polymerization is central to polymer science, yet classical approaches face a trade-off between molecular resolution and computational cost: for copolymers, the number of distinguishable species grows exponentially with chain length. Quantum computing offers a potential alternative, provided the...

Efficient quantum state preparation on Quantinuum hardwareTier 3

Preparation and verification of specific quantum states is an important capability for quantum devices to realise advantages over classical computations and algorithms. In this work, we have demonstrated an end-to-end framework that combines resource-efficient quantum state preparation with rapid, robust fidelity verification on near-term quantum hardware. By experimentally...

Previously: 2026-06-19

Few-body bound states in the anyon-Hubbard modelTier 3

Quantum statistics in low-dimensional systems predicts anyonic particles with fractional exchange statistics which are neither that of bosons nor fermions. While anyons are typically found in two dimensions as excitations of topologically-ordered states of matter, anyon-like exchange statistics has also been discussed in one dimension, for instance, in the context of the any...

Non-perturbative theory of valley splitting in Si qubits from variational wave function: periodic effects of shear strain and asymptotic freedom in the wiggle-well potentialTier 3

Valley splitting sets the energy scale at which spin and valley degrees of freedom hybridize in silicon quantum-well qubits, but its sensitivity to interface structure makes it difficult to predict. Using the valleyor basis, we formulate a two-band effective-mass model for intervalley coupling in a finite quantum well and develop an analytical framework for treating non-pert...

The Forgotten History of Wave Function Variance Optimization and its Relevance for Neural-Network VMCTier 3

We revisit the almost century-old question of which functional of the local energy best optimizes a trial wave function, a problem of central importance in Variational Monte Carlo (VMC) and, more recently, in Neural-Network VMC (NN-VMC). While variance optimization dates back to the 1930s, the high statistical noise and heavy-tailed local energy distributions inherent to mod...

Renormalization of One-Dimensional Semirelativistic Bosons with Contact InteractionsTier 3

We study one-dimensional spinless bosons with semirelativistic spinless-Salpeter dispersion and attractive pairwise contact interactions. Because the dispersion becomes linear at large momentum, the contact interaction is marginal by power counting and produces a logarithmic ultraviolet divergence. We construct the renormalized many-body theory using an enlarged Fock space a...

Semidefinite extension complexity of the separable set, with applications to approximate disentanglersTier 3

We prove quantitative lower bounds on the semidefinite extension complexity of the set of separable quantum states on C^d⊗C^d. We consider semidefinite programs (SDPs) that approximate the maximum acceptance probability of a measurement over separable states, the optimization problem underlying QMA(2). In the extended-formulation model of Harrow, Na...

Hilbert space connectivity in non-Hermitian many-body systems: emergent scale-dependent amplification and constraint-induced skin localizationTier 3

Various exotic many-body phenomena such as quantum scars and fractons have been linked to Hilbert space fragmentation. In this work, we find that in non-Hermitian settings, Hilbert space connectivity has an even more universal and fundamental influence, tightly controlling the nature of spectral amplification and state localization. Far more complicated than real-space latti...

IonQ Uses Investor Day to Detail Superion Roadmap, SkyWater Strategy and Quantum Security PlansTier 2

Time-Dependent Quantum Monte Carlo for fermions: from Bayesian conditioning to spinor dynamicsTier 3

The time-dependent quantum Monte Carlo method represents a many-electron state by an ensemble of replicas, in which each electron is described by a cloud of walkers which samples its density in physical space, one walker and one guide wave per replica, and it replaces the Hartree potential by a conditional interaction built from the walker positions. The sampling is in physi...

QUDORA Joins EuroHPC Quantum Grand Challenge With Near Field Quantum Control ProjectTier 2

IonQ Launches Superion 256 Quantum Computing PlatformTier 2

Green's Functions from Sample-based Krylov Quantum Diagonalization: An Impurity Solver for Dynamical Mean-Field TheoryTier 3

We generalize the sample-based Krylov quantum diagonalization (SKQD) method from ground-state calculations to the evaluation of single-particle Green's functions. By constructing and sampling unitary Krylov subspaces in the N +/- 1 particle-number sectors and evaluating all sector-connecting overlaps classically, the approach reconstructs the Green's function via a Lanczos c...

Large-scale dynamics of integrable quenchesTier 3

The Ballistic Macroscopic Fluctuation Theory (BMFT) is a path-integral based approach to treat large-scale correlations in interacting integrable systems which, so far, has only been applied to quasi-equilibrium settings. In this paper we extend this approach to integrable quench problems and, to illustrate it, we compute the time evolution of the full-counting-statistics (F...

Near-optimal synthesis of non-Gaussian phase gates via qubit-oscillator Rabi controlTier 3

Non-Gaussian gates remain a key bottleneck for universal continuous-variable (CV) quantum computation because the nonlinearities they require are difficult to engineer. To address this challenge, we develop an efficient qubit-oscillator Rabi synthesis scheme for polynomial phase gates, with a total interaction time that scales polylogarithmically with the inverse target erro...

Anderson orthogonality scaling in the Rabi-driven heavy Fermi polaronTier 3

The Anderson orthogonality catastrophe (AOC) is a paradigmatic many-body phenomenon in which a local perturbation induces a macroscopic response of a Fermi sea. We probe signatures of the AOC by coherently driving heavy Fermi polarons in an ultracold ^6Li-^(133)Cs mixture. We observe a power-law dependence of the measured Rabi frequency on the drive strength, with expone...

Impossibility of One-Way One-Round Quantum 4-Coloring via Matrix-Space StabilityTier 3

We show that one-way one-round quantum LOCAL algorithms cannot $4$-color directed cycles with high probability, even with unbounded local computation and quantum message length. This is the first lower bound in the high-probability quantum LOCAL setting that goes beyond the non-signaling and bounded-dependence models, exploiting the structure of distributed quantum algorithm...

Near-Optimal Quantum Lower Bounds for Convex Optimization via Fourier RankTier 3

We establish a near-linear quantum query lower bound for high-accuracy convex optimization over an explicit family of n-dimensional ellipsoids. We focus on linear optimization with an explicitly given objective, where the feasible set is accessed through a membership oracle. We show that any algorithm that, for every unit linear objective, returns an exactly feasible point...

Previously: 2026-08-26, 2026-07-31

Modular commutator as a robust topological invariant and approximate MarkovianityTier 3

The modular commutator provides a bulk, local, single-wave-function probe of the chiral central charge c_- for gapped ground states. Its invariance under deformations was previously established under a local quantum Markov condition---namely, the conditional mutual information I(A:C|B) is zero for all tripartitions of a disk into three consecutive strips A, B, and C \cit...

No information transmission through quantum channels above capacityTier 3

We show that the capacity of a quantum channel demarcates a phase transition: while reliable transmission below capacity is always possible, any attempt to transmit information above it fails catastrophically. Specifically, we prove exponential strong converse theorems for unassisted quantum and classical communication over arbitrary finite-dimensional memoryless quantum cha...

Restart and first detection in a lackadaisical quantum walk with flat-band localizationTier 3

We study stochastic and sharp restart in a one-dimensional lackadaisical discrete-time quantum walk with self-loop weight ℓ. In the absence of restart, the dynamics has a flat band responsible for intrinsic localization and two dispersive bands supporting ballistic propagation. We compare two initially localized benchmark states: a flat-band-active state with finite fla...

Zirconium Carbide as a High-Temperature Benchmark for the Beyond Quasi-Harmonic MethodTier 3

Molar heat capacity at constant pressure, C_p (T), is a central thermodynamic quantity in materials science, but it remains difficult to calculate accurately from first principles when anharmonic vibrational effects become important. In this work, rocksalt ZrC is used as a high-temperature benchmark for the Beyond Quasi-Harmonic (BQH) method, a prepared-supercell first-princ...

On spatial decoherence in many-body systemsTier 3

We study the dynamics of a many-body quantum system strongly interacting with a bosonic reservoir. The coupling is given by a potential operator for the system and it is linear in the field. We show that in the limit of infinite coupling strength the system undergoes instantaneous spatial decoherence. To resolve the decoherence process in time we consider large coupling stre...

A Quantum-Inspired Approach to MaxCut Based on Sparse Walsh/Pauli-Correlation EncodingTier 3

We present a quantum-inspired Walsh/PCE solver for MaxCut based on sparse Pauli-correlation encodings. Instead of assigning one qubit or one variable to each graph vertex directly, the method represents relaxed binary variables through expectation values of diagonal Pauli/Walsh observables. These correlators are computed classically from sparse Walsh autocorrelations, produc...

Distributed Quantum Property Testing with Quantum Carrier PigeonsTier 3

We introduce a framework for distributed quantum inference under communication constraints. In our model, m distributed nodes each receive one copy of an unknown d-dimensional quantum state ρ, before communicating via a constrained one-way communication channel with a central node, which aims to infer some property of ρ. This framework generalizes the classical distr...

Quantum speed limits based on quantifiers of quantum-state textureTier 3

Quantum speed limits impose intrinsic lower bounds on the shortest time scale for quantum system evolution. As an emerging paradigm in quantum resource theory, quantum-state texture has attracted research interest amid the rapid advancement of quantum theory. Herein, we investigate the interplay between quantum speed limits and quantum-state texture via several canonical qua...

Uniqueness and Cramér-Rao Efficiency of Quantum U-StatisticsTier 3

We study unbiased estimation of scalar-valued polynomial functionals of quantum states from independent copies. We establish an equivalence between the first-order marginal of a permutation-invariant finite-copy observable and the functional gradient. We then prove that, among unbiased permutation-invariant estimators, the quantum U-statistic is the unique extension to an ar...

On the Power of Adaptivity in Testing Quantum States in FidelityTier 3

We study the problems of quantum state certification, equivalence testing and independence testing. In certification, given samples of an unknown quantum state ρ and the description of a state σ, the goal is to test whether ρ=σ, or whether ρ and σ are far in a given distance measure. In equivalence testing, σ is also unknown and only accessible via samples. Indep...

Closing the Loop: Non-Causal Computation, Partial Traces, & Postselected EntanglementTier 3

This paper gives a categorical interpretation of Baumeler \& Wolf's logically consistent non-causal circuits, connecting them to postselected quantum teleportation. Looped feedback is represented by a trace in the category of non-negative matrices, and it is shown that the traced process is stochastic precisely when the induced loop transition matrix has trace $1$ for every...

Persistence of measurement-induced nonlocality in uniformly accelerating Unruh-DeWitt detectorsTier 3

Uniform acceleration induces a thermal response to the Minkowski vacuum and can thereby modify quantum correlations. For measurement-induced nonlocality (MIN), a form of nonclassical correlation distinct from entanglement, previous field-mode analyses of bosonic fields found that it decreases with increasing acceleration and vanishes in the infinite-acceleration limit. This...

Causal-Class Hierarchies in Coherence-Constrained Channel TransformationTier 3

Higher-order quantum transformations allow multiple channel uses to be combined through different causal architectures, from parallel and fixed-order sequential networks to general higher-order processes. Whether this causal freedom improves channel transformation when the higher-order operation is also constrained by a resource theory remains largely unexplored. We study th...

Finite-size Entanglement Certification via Third-Order Local Randomized MeasurementsTier 3

Certifying entanglement in high-dimensional systems usually requires full state tomography, whose cost grows rapidly with the system dimension. Local randomized measurements offer a scalable alternative, but existing tests based on second-order correlations access only limited information about the state. Here, we derive a finite-size entanglement certificate that extends lo...

Gravitational decoherence from soft-graviton S-matrixTier 3

We revisit gravitational decoherence of matter superpositions using the leading soft sector of the graviton S-matrix. Starting from Weinberg's soft theorem and the overlap of coherent radiation states, we derive, for branch configurations with the same total four-momentum, a gauge-invariant, nonnegative leading-soft decoherence exponent and evaluate the polarization sum an...

Kinematic Control and Dephasing Dynamics of Quantum Resources in e^+e^-→τ^+τ^-Tier 3

We characterize several quantum resources carried by the spins of the τ^+τ^- pair produced in e^+e^- annihilation. At the Belle-II energy, √s=10.579 GeV, Bell nonlocality, steerability, entanglement of formation, and coherence are governed by the production angle and are largest for transverse emission, θ=π/2. Their common kinematic or...

Deriving the Kijowski Arrival-Time POVM from the Schrödinger Current: Minimal Positivity and UniquenessTier 3

Quantum backflow refers here to the appearance of a negative Schrödinger current for a state whose momentum support is entirely positive. We ask for the smallest modification of the free Schrödinger current that makes it nonnegative for every such state, while preserving the current of each individual momentum component. We show that the required minimal modification changes...

Trapdoor Functions with Secure Key Leasing and Copy ProtectionTier 3

Inspired by the no-cloning theorem in quantum theory, a variety of quantum cryptographic primitives with unclonable functionalities, such as secure key leasing and copy protection, have been proposed and attracted significant attention. However, trapdoor functions (TDFs), fundamental primitives in public-key cryptography, have not been extensively studied in these areas. In...

Performance of the subcarrier-wave quantum key distribution in the presence of spontaneous Raman scattering noise generated by classical DWDM channelsTier 3

In this paper we study performance of the subcarrier-wave quantum key distribution system (SCW QKD) in the presence of spontaneous Raman scattering (SpRS) noise generated by classical channels of dense wavelength division multiplexing (DWDM) network within a single-mode optical fiber. We present the mathematical model for evaluation of the quantum bit error rate (QBER) and t...

A theoretical study of subcarrier-wave quantum key distribution system integration with an optical transport network utilizing dense wavelength division multiplexingTier 3

In this paper we study the performance of subcarrier-wave quantum key distribution (SCW QKD) in the presence of classical channels of optical transport network utilizing dense wavelength division multiplexing (DWDM). We consider the impact of spontaneous Raman scattering noise as well as the four-wave mixing and channel isolation efficiency. We calculate quantum bit error ra...

Dynamics of entanglement in non-Hermitian system of nonreciprocal couplingTier 3

The exploration of the effect of non-Hermitian (NH) in quantum systems is gaining renewed momentum as a result of the recent progress in experiments. It has been indicated that the ability to engineer the orders of exceptional points (EPs) can be fundamental to its applications in quantum control, such as accelerating entanglement generation; however, an initial survey of th...

Scaling-Enhanced Rapid Readout of a Qubit Ensemble Assisted by High-Frequency Detector ModesTier 3

Quantum measurements of large qubit ensembles are often performed indirectly by coupling the ensemble to a detector and subsequently measuring the detector. Despite the importance of rapid collective readout, it remains unclear what determines how the readout time scales with the number of qubits N. Here, we first establish a benchmark N^(-1/2) for a broad class of detec...

Spectral characterization of the uniform theta graph Θ(t,2) and classification of 6-periodic Grover walksTier 3

We characterize the uniform theta graph Θ(t,2) by the spectrum of its normalized adjacency matrix, or equivalently, by the spectrum of its normalized Laplacian matrix. We also investigate the periodicity of Grover walks on nonregular graphs, which is closely related to the eigenvalues of the normalized adjacency matrix and those of the time evolution matrix of the Grover w...

Nuclear slowing-down factors in alkali-metal vaporsTier 3

Nuclear slowing-down factors account for the sharing of angular momentum between the electron and the nucleus in the effective Bloch description of alkali-metal spin dynamics in the spin-exchange-relaxation-free (SERF) regime. For collinear optical pumping and magnetic field, we find that longitudinal and transverse spin dynamics are characterized by different polarization-d...

Asymptotics of Ground States for Helium-Like and Bosonic Atoms in a Two-Cluster RegionTier 3

We study the asymptotic behavior of positive ground states of N-particle atomic Coulomb Hamiltonians in a two-cluster region. For the N-particle ground state ψ, its one-particle density ρ, and (N-1)-particle ground state φ, we show that for 0<α<1, as |x_N|→∞, ψ(x_1,…,x_N)/√(ρ(x_N))= φ(x_1,…,x_(N-1))+O(|x_N|^(-2+α) ln|x_N|) uniformly in...

QNu Labs Raises ₹200 Crore ($25 Million USD) Led by National Quantum Mission And Speciale InvestTier 2

Quantum Startups Among 16 Finalists Selected for Constructor Start Demo DayTier 2

Daniel Freedman Joins Quantum X Labs as Distinguished Quantum ScientistTier 2

PsiQuantum Finalizes $100 Million Award with the U.S. Department of CommerceTier 2