August 31, 2026

Hardware-Efficient Error Mitigation and Shot-Efficient Sampling on IBM Quantum HardwareTier 3

We experimentally study error mitigation and finite-shot sampling on superconducting quantum hardware under a constrained execution budget. The study combines calibration-aware qubit selection, circuit-depth scaling, zero-noise extrapolation, dynamical decoupling, readout-error mitigation, and repeated-shot estimation on an IBM Quantum processor. Experiments are organized ac...

High-Throughput Normalized Min-Sum Belief Propagation Decoding for Quantum LDPC Codes with Near-Memory ProcessingTier 3

Real-time quantum error correction requires classical decoders to process growing syndrome workloads with low and predictable latency. For quantum low-density parity-check (qLDPC) codes, iterative belief propagation (BP) repeatedly updates messages over sparse Tanner graphs, creating substantial memory-access and data-movement demands. We map normalized Min-Sum BP decoding o...

Learning to Decode Concatenated Quantum Codes with Hierarchical Message PassingTier 3

We introduce a neural message-passing framework for decoding general concatenated stabilizer codes. Soft beliefs propagate bidirectionally across concatenation levels, and lightweight neural networks learn only to aggregate incoming messages. For the concatenated [[15,7,3]] quantum Hamming code, the resulting decoder achieves substantially higher thresholds than the state-...

Fabrication-free assessment of microwave losses in germanium-based dielectrics and superconductorsTier 3

We present a flip-chip-based sensing scheme to measure effective microwave losses associated with target materials for quantum technologies, without requiring any device fabrication on the material under test. Using this approach, we quantify the microwave losses of a strain-engineered Ge/SiGe quantum well heterostructure and investigate losses arising from its Ge substrate...

Kerr nonlinearity and three-wave mixing in superconducting resonators hosting Al-InAs weak linksTier 3

Nonlinear microwave resonators are a versatile tool in quantum information processing, enabling parametric amplification, continuous variable quantum computing, and engineered mode interactions. Many of these applications especially benefit from cubic nonlinearities enabling three-wave mixing; at the same time, they are limited by quartic nonlinearities giving rise to undesi...

Crystal-phase quantum dots in AlGaAs nanowiresTier 3

Crystal-phase quantum dots (CPQDs)unicodex2014quantum dots in nanowires defined by crystal structure rather than material compositionunicodex2014constitute the only platform capable of fabricating quantum-dot arrays with the ultimate precision of a single atomic layer. This intrinsic control yields perfectly aligned quantum dots with atomically sharp interfaces, pr...

Postselection-loophole-free Bell test under strict spacetime constraintsTier 3

Entanglement gives rise to correlations between distant quantum systems that cannot be explained by local realistic theories. Bell inequality violations provide a direct way to reveal these correlations and certify nonlocality, especially when the relevant experimental loopholes are closed. Time-bin encoding, in which quantum information is encoded into well-defined temporal...

A quantum generative model for in silico clinical trials using scarce training datasetsTier 3

In silico methods have emerged as a strategy to complement clinical trials. These are particularly relevant for rare or heterogeneous diseases for which traditional methods are costly or difficult to apply. While classical generative models have shown an extremely good ability to generate high fidelity data when trained using extensive databases, they often struggle when the...

Langevin Theory of Non-Markovian Quantum Dynamics: Application to Delayed Coherent Feedback and the Laser LinewidthTier 3

Phase-space methods are powerful tools for the treatment of Markovian open quantum systems: they map the reduced dynamics of a system S, in interaction with an environment E, exactly onto Langevin equations for c-number stochastic variables, as opposed to Heisenberg-Langevin equations for operators. Langevin equations provide analytical insight in key regimes and excel at ha...

Casimir-electrostatic pull-in in nanoelectromechanical actuators: Differentiable design sensitivities and the damping-dependent collapse boundaryTier 3

Nanoelectromechanical actuators operating at sub-100-nm gaps collapse through a pull-in instability set by competing electrostatic and Casimir forces. The quasi-static fold that bounds their safe operating range has been known in closed form for three decades, together with the Casimir ceiling above which no static equilibrium survives, which fixes the smallest gap a given s...

Approaching Resource-Theoretic Optimal Performance with Structured EnvironmentsTier 3

Resource-theoretic approaches to thermodynamics provide powerful, model-independent bounds on the efficiency of physical processes, because they do not rely on microscopic details of the environment. Whether such bounds can be approached by realistic dynamics generated by explicit system-environment interactions remains an open question. Photoisomerization, a fundamental mol...

From quantum reservoirs to quantum extreme learning machines through a nearest-neighbor spin chain with tunable quantum memoryTier 3

Quantum Reservoir Computing (QRC) processes temporal data by retaining a memory of past inputs in the recurrent state of a quantum system, whereas a Quantum Extreme-Learning Machine (QELM) discards that memory, resetting the system at every step so that only the most recent input shapes the response. The two are usually treated as separate computational paradigms. We show th...

Variationally Optimized Imaginary-time Polynomial Filters for Ground State ProjectionTier 3

In this work, we develop a variational imaginary-time evolution (ITE) framework based on polynomial filtering, derived from an operator-level action principle, which yields an optimized non-unitary projector expressed as a polynomial in the Hamiltonian. Starting from a single-ancilla, first-order imaginary-time update defined by a Taylor expansion and Trotter-Suzuki (TS) dec...

Comparing Classical and Quantum Machine Learning for Regression in High Energy Physics Collision DataTier 3

The classification and regression of particle collision events constitute a persistent computational challenge in experimental high energy physics, where large volumes of simulated data must be processed with both speed and precision. This work carries out a systematic comparison of four classical machine learning architectures, support vector machines (SVM), artificial neur...

Vectorized Symmetric and Fermionic Tensor Network Implementations for GPU-Accelerated Variational Monte CarloTier 3

Variational Monte Carlo (VMC) calculations based on tensor networks (TN) have recently achieved competitive accuracy in ground-state calculations of strongly correlated spin and fermionic systems. However, existing tensor network VMC (TN-VMC) algorithms have not been formulated in a manner that can fully utilize GPU acceleration. We tackle the key missing ingredient, namely,...

Benchmarking Quantum Feature Encoding Strategies for Binary Classification with QSVMTier 3

The way in which classical data are encoded into quantum states plays a significant role in both classification performance and quantum circuit complexity in Quantum Machine Learning. In this study, the effects of different quantum feature encoding strategies on Quantum Support Vector Machine performance were investigated using five binary classification datasets. In particu...

S-Transistors Raises €2.6 Million Pre-Seed Round to Introduce Superconducting Transistor PlatformTier 2

Quantum thermodynamics near the border of a one-dimensional Bose gasTier 3

We consider an ultracold Bose gas in a half-open potential well, otherwise confined to a quasi-one-dimensional geometry. The Bogoliubov equations for its elementary excitations are solved in the continuous spectrum to explore the particle and energy content near the edge of the gas, beyond the often applied local density approximation. In particular, gradients in the condens...

Energy Internet Routing using Quantum Optimization AlgorithmsTier 3

The Energy Internet (EI) is a new concept aimed at enhancing the integration of renewable energy sources with the energy grid. Energy-efficient path selection in EI is NP-hard. This research presents an innovative Quadratic Unconstrained Binary Optimization (QUBO) and Ising Hamiltonian formulation for energy routing. The validation and scalability of the proposed formulation...

Optomechanical inertial reference for atom interferometryTier 3

Atom interferometers are among the most sensitive inertial sensors, yet deployment outside the laboratory is limited by vibration noise, conventionally mitigated by external sensors or bulky isolation. Here we demonstrate a hybrid inertial sensor which fuses an optomechanical resonator and an atom interferometer by exploiting the resonator's test mass as the interferometer's...

French National Quantum Update: August 2026Tier 2

How Long-Range Tails Reshape Non-Hermitian SpectraTier 3

Exponentially decaying long-range hoppings are ubiquitous in realistic tight-binding models and are often truncated to obtain a finite-range description. We show that this approximation can fail dramatically in non-Hermitian systems under open boundary conditions: an infinitesimal long-range hopping can nonperturbatively reconstruct the spectrum and eigenstates of a short-ra...

Solvable relaxation in discrete unitary systems: Ruelle-Pollicott resonances and CMV matricesTier 3

Leading eigenvalues of the truncated propagator, known as Ruelle-Pollicott (RP) resonances, are an elegant way of addressing the dynamics of unitary many-body systems. We study unitary propagators in their canonical form, known in the mathematical literature as the CMV matrices, and obtain a number of exact results for RP resonances and the associated norm-diverging eigenvec...

Quantum Fourier transform for the symmetric groupTier 3

Quantum Fourier transforms (QFT) for general groups were recognized to be fundamental already early in the field. A canonical example of non-abelian QFT for the symmetric group was outlined by Beals (1997). Later, a more detailed analysis of this algorithm was carried out by Kawano and Sekigawa (2016). In this paper, we revisit that construction. After a careful analysis, we...

Modifying van der Waals Materials via Cavity Vacuum FluctuationsTier 3

In the field of cavity quantum materials, vacuum fluctuations of optical cavities are used for modifying ground-state properties of quantum materials without external driving. Here, one example is the van der Waals (vdW)/dispersion interaction in layered 2D vdW materials, where non-additive long-range correlations can dominate the interlayer binding. While cavity-induced cha...

Beyond sensitivity: mechanism-resolved error budgets for designing quantum sensorsTier 3

Quantum sensors are specified by a headline sensitivity, yet applications also demand accuracy and reliability. The dominant limiter of one metric is often known, but no method resolves how interacting mechanisms combine into a signed, per-mechanism budget for each metric. We introduce a framework that computes a sensor's sensitivity, accuracy, and robustness from one open-s...

Sufficient positive maps between von Neumann algebras: Rényi divergencesTier 3

We prove recovery theorems for α-z Rényi divergences under normal unital positive maps between von Neumann algebras. Previous results in this setting required 2-positivity, while recent finite dimensional work showed that this assumption can be relaxed to mere positivity. Our proof uses sufficiency for JW*-subalgebras and L^p-spaces over them to characterize equality i...

Input-Output Analysis of Quantum Dot SUPER ExcitationTier 3

The Swing-UP of the quantum EmitteR population (SUPER) two-color pulsed excitation scheme allows for robust and close to 100\% excitation of a two-level quantum emitter using only red detuned light. We analyze the underlying counterintuitive dynamics using a full quantum input-output description of the in- and outgoing light pulses for the case of two coherent free-space inp...

Constant-time equilibration of observables under rapid Lindbladian dynamicsTier 3

Markovian open-system dynamics have widespread applications throughout quantum information science, including algorithmic state preparation. Their convergence is commonly quantified using the worst case global trace distance between the evolving and stationary states. However, this criterion can be unnecessarily stringent when only physically relevant observables are of inte...

Quantum transport and unified scaling law in graphene with polyadic Cantor electrostatic barriersTier 3

We study the quantum transport of Dirac electrons in graphene subjected to a polyadic Cantor-structured electrostatic potential. Using the superperiodic potential formalism, we obtain a closed-form expression for the transmission probability. As the Cantor stage increases, the transmission spectrum evolves from a sparse set of superlattice resonances to a near-transparent re...

A Single Spin Switches the Steady-State Phase of an Open Quantum SystemTier 3

Changing a many-body system by one constituent is normally expected to produce only a vanishing correction to an intensive observable. Here we show that, above a critical dissipation imbalance, adding one spin at fixed intensive controls switches the steady state of a dissipative collective spin between a phase-averaged ring and a south-polar fixed point. Unlike previously p...

Quantum Federated Learning Based on Bures--Uhlmann Geometry for Heterogeneous Noisy ClientsTier 3

Quantum federated learning enables collaborative model training across quantum devices without sharing raw data, and it faces the data and hardware heterogeneity inherent to noisy quantum devices. Utilizing the quantum geometric tensor is a natural remedy, yet pure-state approaches and diagonal approximations discard the correlations that encode parameter incompatibility. To...

Rapid Charge Stability Diagram Generation from Device-level Modeling of Semiconductor Quantum DotsTier 3

Self-consistent Schrödinger-Poisson calculations are a powerful tool for predicting the behavior of layered semiconductor quantum dot devices. However, characterization of charge stability diagrams through fully simulated gate-voltage sweeps is computationally expensive. Combining a Multi-Domain Multi-Model (MDMM) approach with an automated tuning routine, we identify gate v...

Quantum many-body effects in the optical response of ideal thin filmsTier 3

We study quantum many-body effects in the long-wavelength optical response of confined electrons at finite temperatures. We simulate homogeneous electron gas confined in one dimension into a slab of nanoscale thickness. We demonstrate how the slab boundaries break down the ideal Drude response of free charge carriers, giving rise to scattering effects due to both the surface...

Role of the Drive in Mediating Correlations Between Two Qubits Through a Shared Dissipative CavityTier 3

Using a numerically exact master equation, we demonstrate that two qubits, coupled solely through a shared damped, driven cavity, can become correlated. The drive influences both the amount and the type of correlation. For parametric, coherent, and resonantly modulated drives, the qubits develop quantum discord that increases with cavity temperature, while the logarithmic ne...

Engineering Coherence and Ergotropy through Spatial Arrangement of Environmental Channel in a Two-Qubit Quantum BatteryTier 3

We investigate how the spatial arrangement of environment channel influences the dynamics of coherence and work extraction in a two-qubit quantum battery with resonant qubits coupled through an XY-exchange interaction. Qubit B is attached to a finite-temperature thermal bath, while RTN noise is applied either to qubit A or to qubit B, depending on whether it is in a separate...

Self-partitioned Interfacial Time CrystalsTier 3

Nonequilibrium many-body systems can spontaneously break symmetry in time, as in time crystals, or in space, through self-organized domains and interfaces. Whether these two forms of symmetry breaking can intertwine so that an emergent interface alone hosts time-crystalline order remains unknown. In this work, by introducing the Rabi-Hatano-Nelson model, we unveil the existe...

Quantum computation of partonic Drell-Yan scattering cross sections and interference effectsTier 3

We probe the possibilities of efficiently constructing simple Feynman diagrams into quantum devices. More precisely, we study Drell-Yan lepton pair creation at the partonic level of the form q qbar -> gamma/Z -> l- l+. We develop quantum gates that build up the relevant diagrams using simple Feynman rules, such as vertex and propagator gates V and P. We show how the quantum...

Physics-Constrained Conditional Generative Learning for Quantum State and Process TomographyTier 3

Quantum state and process tomography constitute essential diagnostic tools in quantum information science, yet their standard formulations suffer from prohibitive computational scaling as the number of qubits grows. In this work, we introduce a physics-constrained conditional generative adversarial network that bypasses iterative constrained inversion by directly learning a...

Pulsed single-photon magnetometry with a Λ-type three-level system: near-optimal frequency-resolved photon countingTier 3

We investigate pulsed single-photon magnetometry with a Zeeman-sensitive Λ-type three-level system driven by a classical control field. We derive the asymptotic output state and decompose its quantum Fisher information into photon-loss, spectral-intensity, and spectral-phase contributions. Environmental coupling reshapes the scattering response and can increase magnetic-fi...

From integrability to many-body quantum chaos through a Markovian bathTier 3

Recent examples have confirmed the common belief that quantum chaos is always suppressed in the presence of an environment. Here we show that this is not always the case. We compute the Lyapunov exponent of a q-body Majorana Sachdev-Ye-Kitaev (SYK) model coupled to a Markovian bath. Provided that the jump operators describing the bath are isotropic random k > 2-body Majo...

Hybrid Heralded Noiseless Amplification with Finite-Cutoff Quantum ScissorsTier 3

A noiseless linear amplifier (NLA) can probabilistically amplify an optical state without the noise required by deterministic phase-insensitive amplification. We study a hybrid amplifier in which a finite-cutoff quantum-scissor NLA is placed between two single-mode squeezers. Analysis based on an ideal (infinite cutoff) NLA finds a gain enhancement from the squeezing. We exp...

Quantum Fourier transform toolboxTier 3

Quantum Fourier transforms (QFTs) are essential primitives in quantum algorithms. While abelian groups admit efficient QFT circuits, with circuit size polynomial in the logarithm of the group order, efficient constructions are known for relatively few non-abelian families. We develop two new approaches to QFT circuit construction, based on Mackey theory and Clifford theory,...

Quantum geometric bounds at finite temperature for one-dimensional chiral systemsTier 3

The geometry and topology of quantum states are intimately related at zero temperature through exact bounds that constrain geometric quantities from below by topological invariants. At finite-temperature, however, the analogous relations remain unclear. Here we establish rigorous geometric lower bounds for one-dimensional (1D) chiral-symmetric systems at finite temperature w...

Direct Adaptive Certification of High-Dimensional Entanglement with Bell TestsTier 3

Entangled photons play a crucial role in quantum applications, and determining and characterising their entanglement is vital to using them effectively. High-dimensional entangled states offer richer possibilities, but their additional measurement degrees of freedom make them increasingly demanding to characterise. However, adaptive Bell-test methods based on complex simulta...