June 4, 2026

High-fidelity neutral atom gates leveraging low-rank Hessian optimization

Quantum optimal control can produce fast and robust multi-qubit gates, but experimentally calibrating the resulting high-dimensional waveforms remains challenging because direct searches over large parameter spaces converge slowly. Building on the low-rank structure of quantum-control landscapes, we develop and benchmark a Hessian-based calibration method for optimal-control...

Measuring Entanglement in Qubit System

An operational way of measuring entanglement in a balanced two-path interferometers is presented, where path information is carried by some internal degree of freedom which, in turn, gets entangled with an ancilla system. The analysis is based on a tripartite description involving paths, an internal qubit degree of freedom, and some ancillary states entangled with the intern...

Generalized Bicycle Codes as Cyclic Submodules and their Automorphism Structure

Automorphisms of quantum codes, when they exist, offer a pathway toward fault-tolerant gate implementation via qubit relabeling. Although useful, the conditions under which automorphisms appear in a given code remain poorly understood. In this paper, we develop an algebraic framework for systematically analyzing and engineering automorphisms in Generalized Bicycle (GB) codes...

Gaussian mean width strong converse bound on the classical identification capacity of quantum channels

We establish a single-letter and efficiently computable strong converse bound on the classical identification capacity of quantum channels. By equipping the n-fold channel output space with a product state-weighted σ-Euclidean geometry, we allow trace-distance separation constraints for identification codes to be controlled by Euclidean covering estimates. Using Sudakov'...

Measurement-induced state transitions in multi-qubit transmon processors

Dispersive readout of the transmon qubit in circuit QED is known to lose its quantum non-demolition character at small to moderate measurement drive amplitudes. This phenomenon is understood to originate from Laundau-Zener transitions at accidental multi-photon resonances, where n drive photons can promote the transmon by m levels. This interpretation has been shown to b...

Tunable Resonator Integrated Magnetometry

The quantum-technology revolution is reshaping computing, sensing, and communication. In magnetometry, recent advances leverage precise control of spin qubits and color centers in solid-state crystals for mesoscopic-scale sensing. Yet at very low temperatures, superconducting sensing technology remains unrivaled because of its non-invasiveness and higher sensitivity. Here we...

Effect of isotropic errors on the complexity of Grover's algorithm

Isotropic errors have been shown to be immune to conventional error correction techniques. While general theoretical frameworks have been proposed to model such errors, there have been no studies so far analysing their concrete impact on practical use-cases. Here we explore the effect of isotropic errors on the complexity of Grover's search algorithm through numerical simula...

Anisotropic Rabi Model as a Noise Biased Qubit

We present the quantum anisotropic Rabi model as a potential resource for a noise biased qubit. The system-environment coupling can be biased by tuning the relative strengths of the rotating-wave and counter-rotating-wave interactions, characterized by the anisotropy parameter η. This anisotropy selectively suppresses dominant decoherence pathways, thereby enabling the con...

Variational low-energy subspaces for chemically accurate excited states

Accurate electronic excited states are essential for photochemistry, spectroscopy and non-adiabatic molecular dynamics, but high-level calculations often scale steeply and require prior knowledge of the target state's character or symmetry. Here we show that variational excited-state optimization can be reformulated as an iterated ground-state-like problem for a low-energy s...

An Entanglement Measure from Quantum Optimal Transport

We propose a bipartite entanglement measure E(ρ) defined as the minimal order-1 quantum Wasserstein distance from a state to the set of separable states. Owing to the universal data-processing inequality of the Wasserstein metric, the measure satisfies all fundamental axioms within a single geometric framework. A Lipschitz dual formulation yields explicit lower bounds for...

Expressibility, Noise, and Error Mitigation in VQE Ansatz Selection

The variational quantum eigensolver (VQE) is a promising algorithm for near-term quantum chemistry applications, but selecting optimal ansatz circuits remains challenging. Expressibility, a metric quantifying a circuit's ability to explore the Hilbert space, has been proposed as a guide for ansatz selection, but recent work showed it inconsistently predicts VQE performance u...

Pushing the Classical Frontier of 1D Fermi-Hubbard Quench Dynamics Beyond Current Quantum Simulations

Establishing quantum advantage requires comparison against the best achievable classical simulation. The Q-CTRL team recently simulated quench dynamics of the one-dimensional Fermi-Hubbard model on an IBM processor, completing a L=60 evolution to time t=6 in under three minutes and claiming a 3000× speedup over classical Time-Dependent Variational Principle (TDVP)...

Digital Quantum Reservoir Computing for ATM Time Series Prediction

We investigate a digital quantum reservoir computing (QRC) framework for multi-step forecasting of automated teller machine (ATM) cash demand time series on near-term quantum devices. The proposed approach uses parametrized four-qubit reservoirs with a fixed structure exploiting partial measurement and reset, where temporal data is encoded in rotation angles. Training is res...

Hybrid quantum-classical physics-informed neural networks for solving nonlinear PDEs: when and where hybridization is effective?

Physics-informed neural networks (PINNs) often struggle on nonlinear partial differential equations (PDEs) with sharp gradients, stiff dynamics, high-frequency content, or multiscale structure. Such limitations, rooted in spectral bias, ill-conditioned optimization, and unstable convergence, restrict PINN accuracy in regimes where advanced solvers are most needed. In this wo...

Extremely slow scaling of minimal Hamming distance in quantum sampling data

Quantum data can be obtained from a diverse range of sources, including direct measurements from noisy quantum processors, cold-atom simulators, and classical approximations such as variational neural-network states. However, our ability to characterize these systems is fundamentally limited, as the available measurement data is often sparse compared to the exponentially lar...

Distributed Variational Quantum Optimisation by Entanglement-Selective Transport

Distributed quantum optimisation is challenging because computing the problem cost function across multiple quantum processors requires non-local gates, which can incur overhead in latency and fidelity. Here we introduce QESTO, a distributed variational ansatz for graph-based discrete optimisation that requires only persistent pre-shared Bell pairs for remote operations. Usi...

Experimentally probing the Quantum Physics in the Inverted Harmonic Oscillator

When a quantum system passes through an unstable fixed point the local dynamics reduces to the inverted harmonic oscillator (IHO). It exponentially amplifies along one quadrature while squeezing the other, producing macroscopically extended quantum states from microscopic zero-point fluctuations. We realize this dynamics with a Bose-Einstein condensate on an AtomChip. Radio-...

Circuit-Level Noise Estimation via Shuttling in Plaquette Circuits

We present a method for estimating QEC circuit-level noise levels assuming that only single-shot measurements are available (e.g. measurements are slow and performed in a zoned/parallel fashion), and that lower level quantum hardware calibration is not possible (e.g. cloud access) or not feasible (e.g. large scale computing). We develop and run surface code plaquette experim...

High Q Technologies and Creative Biostructure Partner to Deploy Quantum-Enabled EPR Spectroscopy

High Q Technologies and structural biology contract research organization Creative Biostructure have formed a strategic partnership to expand research access to electron paramagnetic resonance (EPR) spectroscopy systems. The collaboration integrates High Q Technologies' FATHOM® EPR platform with Creative Biostructure's experimental design and analytical workflows. The joi...

Finland Allocates €6.9 Million ($8 Million USD) to Launch QScale Consortium for Optical Quantum Control and Cryogenic Packaging

A multi-institutional Finnish research consortium has been awarded funding under Business Finland’s Rise to the Challenge program to launch the QScale project (“Scaling up quantum computing by telecom-based technologies”). Backed by a total budget of €6.9 million ($8 million USD)—including a €5.5 million ($6.4 million USD) primary grant from Business Finland—the three-yea...

Quantinuum to Debut on Nasdaq After Raising $1.68 Billion in IPO

Ooredoo, HBKU, Ministry of Defence Launch Qatar’s First Quantum-Safe Network

Floquet-Engineered Parity Anomaly Staircase in a Cold Atom Dirac Lattice

We propose a Floquet-engineered cold atom realization of a parity anomaly inspired anomalous Hall staircase in a two dimensional π-flux lattice. The effective model hosts massive Dirac fermions generated by the combined action of a time reversal symmetry breaking Floquet mass and a static inversion breaking mass offset. An additional momentum dependent scalar displacement...

Quantum Time Lower Bounds by Permutation Invariance

Tight bounds on quantum sample complexity and quantum query complexity have been known for various computational problems in the literature, whereas tight bounds on quantum time complexity (i.e., the size of quantum circuits) remain unresolved. In this paper, we provide a framework to establish lower bounds on the quantum time complexity for testing permutation-invariant pro...

No-Go Theorem for Gaussian Quantum Repeaters from Fractional Extendibility

Photon loss in optical channels fundamentally limits long-range reliable quantum communication. A standard approach to overcoming this limitation is the use of quantum repeater nodes, which typically perform experimentally demanding non-Gaussian operations. However, whether Gaussian repeater protocols can enhance quantum communication rates over bosonic attenuation channels...

Soliton-antisoliton pairs in the supersymmetric gapped phase of an interacting Majorana chain

A strongly interacting chain of Majorana fermions realizes the supersymmetric tricritical Ising phase, with supersymmetry (SUSY) extending into a symmetry-broken ordered phase adjacent to the tricritical point. Although the signatures of SUSY at the tricritical point are well understood, their behavior in the gapped phase remains less clear. Here, we address two key question...

Squeezed Phonon Lasing via Floquet-Controlled Solid-State Defects

We propose a general Floquet-engineered scheme for phonon lasing that enables a continuous transition from conventional lasing to phase-locked squeezed phonon lasing. Focusing on a solid-state platform based on color centers embedded in a circular hexagonal boron nitride (hBN) membrane, we demonstrate that a mechanical oscillator coupled to principal and ancilla spins, and c...

Fermionic non-Gaussianity via Bell sampling: monotones and efficient quantum algorithms

Fermionic non-Gaussianity is an essential resource for unlocking the full computational power of fermionic quantum platforms. In this work we develop monotones and efficient quantum algorithms for fermionic non-Gaussianity, all built on the eigenvalue structure of the operator Λ= Σ_(j=1)^(2n)γ_j⊗γ_j defined on two copies of an n-mode fermionic state, accessible...

Crossover from Rabi oscillations to adiabatic population switching in the Faraday optical control of quantum dot spins

Stimulated Raman transitions in Faraday geometry allow for simultaneous single-shot qubit readout and qubit control. It involves driving an unbalanced Λ system via an auxiliary excited state. Due to the simultaneous driving of both transitions with unequal detuning, the resulting time-dependent Stark shift gives rise to additional resonance conditions beyond the convention...

A thorium-229 optical nuclear clock with feedback loop

The laser-accessible nuclear transition in the thorium-229 isotope has been identified as a promising candidate for the realization of an optical nuclear clock. Such a nuclear clock might rival or outperform current optical clocks based on electron-shell transitions in atoms or ions, is expected to be more robust against external perturbations, and provides enhanced sensitiv...

Phase-correlation-free quantum key distribution source operating at gigahertz rates

Phase randomization is essential for the security of practical decoy-state quantum key distribution (QKD) systems. Commonly, implementations rely on laser sources which are either actively phase-randomized, or gain-switched. However, at high repetition rates these show correlations, which can ultimately compromise security and performance. We present a 1.25 GHz phase-randomi...

Convergence rates of Sum-of-Hermitian-Squares Hierarchies for the Pauli algebra

Moment/Sum-of-Hermitian-Squares relaxations for noncommutative polynomial optimization problems have become an important tool for analyzing problems within quantum theory. Despite their widespread success, little is known about their rate of convergence and, consequently, their accuracy. In this work, we develop explicit convergence rates for relaxations of noncommutative po...

Decoded Quantum Interferometry Beyond Hamming: Rank-Metric and Translation Association Schemes

Decoded Quantum Interferometry (DQI) uses coherent decoding and a quantum Fourier transform to find high-quality solutions of structured optimisation problems. Existing analyses are closely tied to Hamming space, which underlies the optimisation objective, Dicke state preparation and the decoding step of the algorithm. Here we extend the core DQI mechanism beyond Hamming spa...

Reconciliation of effective Hamiltonians for intense light-matter interaction

Essential-state models are central for quantum control and technology in broad regimes of light-matter interaction. The canonical effective Hamiltonian is obtained equivalently from adiabatic elimination, the Markov approximation, and the pole approximation. These approximations are known to break down at high intensities, significantly limiting their applicability to modera...

Polalrized reservoirs in dynamics of polariton condensation

We review the problem of description of the dynamics of driven-disspipative spinor polariton condensates, focusing on the terms corresponding to the coupling between a macroscopic wavefunction of the condensdate and incoherent excitonic reservoir created by a non-resonant pump. We demonstrate that the existing version of the theory breaks down in case, when reservoir has non...

Photoelectron spectroscopy with a resonant dichromatic field: Role of geometric phase

We investigate geometric-phase control in resonantly driven two-level atoms exposed to near-degenerate dichromatic laser pulses. In contrast to conventional two-color schemes based on widely separated frequencies, the closely spaced frequency components generate a slowly varying beating envelope that repeatedly reverses the pseudo-spin rotation on the Bloch sphere. This enab...

Monitored chaotic scattering

We extend the random-matrix theory of chaotic scattering to quantum dots whose dynamics is monitored by time-resolved measurements. Starting from a scattering matrix drawn from a circular ensemble, we construct the corresponding ensemble of Kraus operators for the monitored evolution of the many-body density matrix. In the single-particle sector the sum over measurement outc...

Resource-efficient energy-based operator selection in fermionic ADAPT-VQE via exact Hamiltonian transformation

The energy-based approach to operator selection in ADAPT-VQE relies on reconstructing the one-parameter energy landscape for each operator in the pool. In fermionic implementations, the cost of reconstructing this energy landscape often becomes a bottleneck. We address this issue through an exact Hamiltonian transformation that reformulates the one-parameter energy landscape...

Imaginarity witness

Imaginarity has shown to be an important resource in quantum information. The witness theory of quantum resource, such as entanglement witness, coherence witness, and imaginarity witness, has been established, in particular entanglement witness and coherence witness have been extensively explored. We present here another class of imaginarity witnesses beyond the one in [{Phy...

Comment on "Possibility of superradiant neutrino emission by atomic condensate" by M. Blasone, L. Gastaldo and F. Romeo, Phys. Rev. D 113, 053010 (2026)

We show that the recent proposal for superradiant emission of neutrinos cannot evade our proof that superradiant neutrino emission is fundamentally impossible. Pairing two fermions in a molecule does not remove the cancellation of interference terms in neutrino emission due to fermionic anticommutators.

Efficient Description of Parametric Amplification of Quantum Pulses

A single quantum pulse undergoing parametric amplification feeds into at most two pulses in the output. In this work, we present an efficient, analytical method for finding the quantum state of these output modes. Our method applies the amplification to the vacuum rather than to the input state, and subsequently applies a transformed version of the operator that creates the...

Quantification of Entanglement in Three-Qubit Systems

This study presents an analytical investigation of entanglement quantification in three-qubit pure states through the Acín canonical representation, which serves as a generalization of the two-qubit Schmidt decomposition. Driven by the intricacies of multipartite entanglement and the shortcomings of current measures, we employ a global concurrence measure derived from the ge...

QPredSGG: Hybrid Quantum Predicate Learning for Long-Tailed Scene Graph Generation

Scene Graph Generation (SGG) requires relational reasoning over objects and their interactions, but performance is often limited by severe long-tail predicate imbalance. Classical SGG models frequently rely on dataset statistics, leading to biased predictions toward frequent relations rather than fine-grained semantic predicates. Although existing debiasing strategies improv...

Protecting Quantum States via the Super-Zeno Effect and Anticoherence

We consider a spin system coupled to a noisy environment via an interaction Hamiltonian H which is a polynomial of degree n in the spin operators S_i (n-magnetic Hamiltonian), and show that the use of the quantum super-Zeno effect in conjunction with a spin-anticoherent subspace, is highly effective in protecting the spin from the noise. When n=1, as in the case of...

Electron-Ion Path Integral Monte Carlo with Hard Core

We performed numerical (restricted) path integral Monte Carlo experiments on metallic Hydrogen from first principles. We study a quantum two component plasma where one component is made of pointwise particles of negative unitary charge and the other is made of charged hard spheres of positive unitary charge. We study both the additive mixture and a nonadditive mixture where...

Nonreciprocal Dispersive Coupling for Quantum Sensing

Dispersive coupling is widely utilized for quantum information readout. Most prior studies have concentrated on reciprocal dispersive coupling. Here, we further construct nonreciprocal dispersive coupling and apply it to quantum sensing. For cavity photon number measurement, nonreciprocal dispersive coupling delivers higher precision than its reciprocal counterpart, and this...

Probing PbTe-Pb nanowire devices with radio-frequency reflectometry

We report the implementation of radio-frequency (rf) reflectometry on selective-area-grown PbTe-Pb nanowire devices on a CdTe substrate. These nanowires were predicted to host Majorana zero modes. We demonstrate the compatibility of the rf technique, both resistive and capacitive sensing, with these nanowires. The effect of dielectric loss from the CdTe substrate is also dis...

Arbitrary manipulation of nuclear spins in hexagonal boron nitride

Due to its localized nature and controllability, the negatively charged boron vacancy centers (V_B^-) in hexagonal boron nitride (hBN) are a promising spin platform for accessing its neighboring nuclei with potential for performing quantum computational tasks. However, the methods of utilizing and manipulating the nuclear spins are still lacking. In this work, we pr...

Multi-entropy in random tensor networks

We study the evaluation of Rényi multi-entropies S^((q))_n in Random Tensor Network (RTN) states in the large bond-dimension limit. For the case of Rényi index n=2 and arbitrary number of parties q, we prove that that multi-entropies are determined by minimal multiway cuts through the network. When the minimal multiway cut is degenerate, we characterize the full minimi...

Atom Interferometry with Transverse Optical Modes

We experimentally demonstrate atom interferometry using the transverse phase profile of an optical mode. As proof-of-principle, we use the helical phase windings of Hypergeometric Gaussian beams for Ramsey interferometry with ensembles of ballistically-expanding cold Rb87 atoms, and we show that the interferometer can measure rotations induced by a motor with a sensitivity t...

Leggett-Garg test inequality with spin and flavour neutrino oscillations in a constant magnetic field

The Leggett-Garg inequality (LGI), an analogue of Bellś inequality involving correlations of measurements of one observable on a system at different times, stands as one of the hallmark tests of quantum mechanics against classical predictions. In this work, we investigate its implications in the context of neutrino flavour (ν_e^Lleftrightarrowν_μ^L) and spin ($ν_{e}...

Optimizing the Sensitivity-Noise Trade-off in Non-Hermitian Sensing via Off-Exceptional-Deficiency Operation

A central challenge in non-Hermitian sensing is that spectral singularities simultaneously amplify both the signal and environmental noise. We address this predicament in a double-chain Hatano-Nelson model featuring unidirectional interlayer coupling. At the exceptional deficiency (ED) limit, the system exhibits a macroscopically degenerate complex spectrum and a pronounced...

Photon shot-noise-limited Rydberg-EIT electrometry

Rydberg-atom electrometry is a core technique in the development of highly sensitive quantum electric-field sensors. Its sensitivity based on atom-photon interaction is typically limited by photon shot-noise (PSN) and spectral broadenings. Here, we experimentally demonstrate a near PSN-limited Rydberg electrometry from a 85Rb atomic vapor cell. By engineering atomic coherenc...

Quobly Closes €115 Million ($133.5 Million USD) Series A to Industrialize Silicon-Spin Qubit Processors

Grenoble-based hardware venture Quobly has finalized a €115 million ($133.5 million USD) Series A financing round to transition its silicon-based quantum computing architecture from technology validation into active industrial execution. The capital expansion was co-led by Bpifrance (investing via the Deep Tech 2030 fund under the France 2030 initiative), post-quantum cyb...

Quantum Design Completes Acquisition of Qnami to Expand Nitrogen-Vacancy Diamond Sensing Portfolio

Quantum Design International, Inc. has finalized the acquisition of Basel-based hardware developer Qnami, marking its second corporate consolidation action of 2026. The transaction integrates Qnami's proprietary diamond-based quantum sensing assets into Quantum Design's global scientific instrumentation portfolio. The acquisition follows Quantum Design's January 2026 proc...

Ooredoo Implements Quantum Key Distribution Link on Qatar’s Core Dark Fiber Infrastructure

Ooredoo Qatar, in a joint national initiative with Hamad Bin Khalifa University (HBKU) and the Ministry of Defense, has completed the deployment of Qatar’s first quantum-safe communications link. This infrastructure project establishes a fully operational, end-to-end Quantum Key Distribution (QKD) framework integrated directly into a live telecommunications environment. D...

Infineon Integrates Certified OPTIGA TPM into NVIDIA Jetson Thor to Secure Autonomous Fleet Frameworks

Infineon Technologies AG has integrated its OPTIGA™ Trusted Platform Module (TPM) SLB 9672 with NVIDIA’s Jetson Thor processing platform. Designed to isolate cryptographic assets and monitor system state parameters at the silicon level, the hardware module serves as a certified root of trust for robotics and Physical AI systems. The architecture provides robotic fleet ope...

Qunova Computing Joins Japan’s JHPC-quantum Test User Program to Deploy High-Precision Chemistry Solvers

Quantum software developer Qunova Computing has signed a Memorandum of Understanding (MoU) to join JHPC-quantum (Japan High-Performance Computing), a national quantum-supercomputing convergence project funded by the New Energy and Industrial Technology Development Organization (NEDO). The agreement designates Qunova as an official participant in the initiative's Test User...

C12 Introduces Nanoassembly Process for Carbon Nanotube Quantum Chips

QuantX Labs Announces Seed Round With Serendipity Capital Lead Investor

Quantum Design Acquires Quantum Sensing Company Qnami

Illinois Quantum and Microelectronics Park Appoints Philip Makotyn as Deputy CTO

Infineon Advances Post-Quantum Security for Robotics Applications

AI-Powered Quantum: Microsoft Turns to Agentic AI to Speed Quantum Computing Push