September 29, 2026

Circuit-level benchmarks of GKP-concatenated qLDPC CodesTier 3

Scalable fault-tolerant quantum error correction based on Gottesman-Kitaev-Preskill (GKP) codes requires finite-rate outer codes that can exploit analog GKP information under realistic circuit noise. However, quantum low-density parity-check (qLDPC) outer codes have not been systematically compared as candidates for circuit-level GKP concatenation. Here, we benchmark BB and...

A Si-on-SiC Platform for Interfacing with Vanadium Dopants in the Telecom O-BandTier 3

Vanadium color centers in silicon carbide (SiC) offer telecom O-band emission, sub-microsecond optical lifetimes, and second-scale spin relaxation times, rendering them promising candidates for quantum network nodes. However, efficient photon extraction from the high-refractive-index SiC host remains challenging. Here, we introduce a silicon-on-SiC heterogeneous photonic pla...

Experimental quantum-computing-enhanced sensing using Grover's algorithmTier 3

The combination of quantum sensing with quantum computing to provide an enhancement over conventional quantum sensing has recently emerged as a promising potential application of quantum computing that could give advantages without needing large-scale or fault-tolerant hardware. In this work, we report an experimental demonstration of a recent theoretical proposal to repurpo...

Electrothermal behavior of superconducting nanowires buried in a commercial CMOS processTier 3

Superconducting films native to a commercial CMOS process enable co-integration of superconducting devices (high-kinetic-inductance elements and nanowire detectors) with cryogenic CMOS on one monolithic die. Such films are buried in the front-end-of-line, beneath the back-end-of-line metal stack, an environment that might quench a self-heated hot spot. Current-voltage charac...

QC-Stark: A Multi-Task Benchmark Revealing Capability Dissociations in LLMs Evaluated on Quantum Computing TasksTier 3

We introduce QC-Stark, a benchmark for evaluating large language models (LLMs) on 11 quantum computing (QC) tasks, spanning circuit construction, debugging, compilation, error correction, and simulation. Across 2,750 evaluations (10 models × 11 tasks x 5 difficulty levels x 5 seeds), we find that overall rankings mask substantial per-task variation. The Spearman corre...

An Exact Polynomial Task-Risk Bridge for Time-Multiplexed Photonic Quantum ReservoirsTier 3

Time-multiplexed (TDM) photonic reservoirs are usually judged by their scores on a few datasets, which say little about a chip's overall performance, and designed by enumerating candidate circuits and simulating each one, which is inefficient and gives no guarantee of finding a good structure. For a time-unrolled passive linear network with data-modulated gates or sources an...

Computational Complexity of Clifford Template Compilation: Are Quantum Computers Useful for Compiling Quantum Circuits?Tier 3

A Clifford template is a finite ordered family of repeatable Clifford operations, and an instantiation specifies how many times each operation is applied. The Clifford template compilation problem asks how to choose these repetition numbers so that the template realizes a target transformation of Pauli operators. This problem arises, for example, when searching for logical o...

Generating Vector-Vortex γ Photons by Nonlinear Compton ScatteringTier 3

Vector-vortex photons, characterized by a nonseparable coupling between polarization and orbital angular momentum (OAM), offer opportunities for optical manipulation, quantum communication, nuclear photonics, etc. However, their generation in the γ-ray regime remains challenging. Here, we put forward a novel method to generate vector-vortex γ photons via nonlinear Compto...

Bounding Retraining Equivalence and the Deletion Floor in Materials Machine UnlearningTier 3

In materials machine learning, closely related retained structures can sustain accurate property predictions even after removing a specific record, rendering post-deletion prediction error an ambiguous metric for machine unlearning. To resolve this ambiguity, we define the deletion floor as the expected target loss under a specified retraining procedure at the deleted reques...

Fourier-Geometric Circuit Design for Gate and Entanglement Placement in Quantum Neural NetworksTier 3

The output of a parameterized quantum circuit (PQC) can be expressed as a finite Fourier series whose accessible frequencies are fixed by the data-encoding gates. While the encoder determines which frequencies can appear, the corresponding Fourier coefficients depend on how the trainable and entangling gates are arranged. Although existing studies provide metrics for charact...

Improving the Stability of the Hierarchical Equations of Motion for Open Quantum Systems with Strong Coupling to Structured Bosonic BathsTier 3

The hierarchical equations of motion (HEOM) approach is one of the most powerful methods avail- able to simulate the dynamics of open quantum systems. Although the HEOM approach has been shown to be stable and efficient in many parameter regimes and physical scenarios, it is also well known that the unavoidable finite truncation of the hierarchy can lead to fundamental numer...

A technological capability scale for civilizations from the Kardashev and Barrow scalesTier 3

We introduce a technological capability scale that ranks civilizations by the control operations they can perform per second. A control operation is defined as setting one binary degree of freedom of matter to a specified value, whatever its previous state. Building on constructor theory, we sort them into construction and its special cases on information media, namely proce...

Classical Bound on the Fisher Information Rate of a Dephasing-Enhanced Quantum NeuronTier 3

Dephasing can sharpen the activation of a dissipative quantum neuron, but a stationary response does not determine how much input information its output delivers per unit time. For a single qubit with partial-reset updates at rate ν, we derive the threshold response bandwidth and the exact local Fisher information rate of the complete record from repeated projective readou...

Simulation-Based Quantum System Inference with Neural Posterior EstimationTier 3

Models of quantum systems faithfully map system parameters to observations, but the inverse problem of parameter inference from measurement data presents a fundamental challenge: computationally intractable likelihoods due to an exponentially large Hilbert space. Here, we introduce simulation-based quantum system inference, a unified, likelihood-free framework that learns pa...

Dilation theorem for continuum quantum stochastic processesTier 3

Connecting mathematical formalism in open quantum systems to its underlying physics necessitates the notion of a dilation, a way to bridge stochastic dynamics with deterministic Schrödinger evolution on a larger space. Although dilations are well known in the literature for states, channels, and quantum combs, there is a substantial gap when it comes to the fully general set...

Enantiomer-specific pumping of chiral molecules in high-J rotational statesTier 3

Enantiomer-specific state transfer (ESST) based on electric-dipole transitions has attracted considerable interest in the studies of manipulating molecules with electromagnetic fields. It also holds promise as a powerful tool for enantiomer detection and separation. To date, experimental demonstrations of ESST have focused mainly on molecules in the lowest rotational angular...

FSU Receives $2.1 Million for Quantum Communication TestbedTier 2

Insider Brief PRESS RELEASE — Florida State University will establish a campus-scale quantum communication testing platform with $2.1 million in federal Community Project Funding through the National Institute of Standards and Technology, secured with support from U.S. Rep. Daniel Webster of Florida’s 11th Congressional District. The testbed will link a central quantum...

CEA-Leti and Quobly Strengthen Their Collaboration to Accelerate the Development of Next-Generation Silicon Quantum TechnologiesTier 2

Insider Brief PRESS RELEASE — Quobly, a French company developing silicon-based quantum computers, and CEA-Leti, a leading research institute in microelectronics and information technologies, are strengthening their long-standing collaboration through access to the FAMES Pilot Line, which complements Quobly’s industrial collaboration with STMicroelectronics and support...

UCL and Siloton Adapt Quantum-Enabled Eye Imaging for ChildrenTier 2

Insider Brief PRESS RELEASE — Researchers at the University College London (UCL) Great Ormond Street Institute of Child Health are teaming up with Bristol-based start-up Siloton on a project that could help prevent sight loss in children by adapting a groundbreaking new eye imaging technology. With funding from the National Institute for Health and Care […]

Analysis of asymmetric errors in NISQ experimentsTier 3

This paper continues our analysis of NISQ experiments and especially the Google 2019 ``quantum supremacy" experiment. In arXiv:2008.05177 we proposed statistical tools to analyze symmetric and asymmetric readout errors, and the symmetric case was extensively developed and studied in arXiv:2404.00935, where we used Fourier methods combined with statistical tools. Here we exte...

Deployment of Large IQP Circuit Born Machines on Qubit-Limited Hardware Using Noise InjectionTier 3

Quantum circuit Born machines (QCBMs) built with instantaneous quantum polynomial (IQP) circuits have loss functions that can be efficiently estimated classically, but require quantum computers during inference. Thus, classical computers can train large IQP QCBMs that exceed the qubit numbers of available quantum hardware. This motivates research into how qubit-limited quant...

Occam Foundry Gains Austin and UT Austin Support for Quantum CampusTier 2

Insider Brief PRESS RELEASE — Occam Foundry, a commercialization campus for quantum technology planned for 16.5 acres in southeastern Travis County, announces a letter of support from Austin Mayor Kirk Watson and a signed memorandum of understanding with The University of Texas at Austin, acting through the Texas Advanced Computing Center (TACC). In a letter […]

KIST Connects Korean Quantum Startups With U.S. Partners at QWC 2026Tier 2

Insider Brief PRESS RELEASE — The Korea Institute of Science and Technology (KIST) has successfully led a delegation of South Korean quantum deep-tech startups at Quantum World Congress (QWC) 2026, establishing key international partnerships and expanding their footprint into the U.S. market. Serving as the lead organization for the quantum technology sector under Sout...

Multilevel Plaquette-Space Sampling for Lattice Gauge Theories with Local Constraint SolvesTier 3

Lattice gauge theories are an important class of physical models with high-dimensional structured distributions that underpin first-principles calculations in particle, nuclear, and condensed-matter physics. Recent advances in generative modeling have opened new avenues for sampling Boltzmann distributions in lattice gauge theories, offering the potential to alleviate limita...

Speed-Fisher Information: Chaos and Irreversibility in Classical and Quantum DynamicsTier 3

We propose a unified perspective on classical and quantum chaos based on the sensitivity of a system's stationary states to slow driving. We probe this sensitivity via the system's susceptibility to the average protocol speed, which we call the ``speed-Fisher information," and relate it to irreversible entropy production in the system. We show that chaotic dynamics manifests...

Optimal Query Complexity for Ground-State PreparationTier 3

We determine the optimal query complexity of ground-state preparation to trace-distance error ε when an energy threshold in the spectral gap is known. Let U_H be an α-block-encoding of a Hamiltonian with unique ground state |ψ_0⟩, and suppose |⟨ψ_0|U_I|0⟩|≥γ for a state-preparation oracle U_I. The threshold lies at least Δ/2 above...

An Optimal Quantum Linear Systems AlgorithmTier 3

In the quantum linear systems problem (QLSP), we are given query access to a d-sparse N×N matrix A with condition number κ, and the ability to prepare a quantum state proportional to a vector b. The goal is to output an ε-approximation to the quantum state proportional to the solution x of Ax=b. Following a long line of work, the b...

Optimal performance in a chaotic Floquet quantum batteryTier 3

We study a quantum battery consisting of N qubits interacting uniformly with each other. Starting from its ground state, the battery is charged by introducing periodic kicks in the transverse direction along with adding disorder in the interaction direction. Although the battery Hamiltonian along with the initial state preserves the permutation symmetry, the dynamics in pr...

Succinct Arguments for QMA from Collapsing Hash FunctionsTier 3

We prove the existence of succinct arguments for QMA, assuming only the existence of collapsing hash functions. This is the first scheme that relies only on unstructured ``Minicrypt'' assumptions, which are not known to imply public-key encryption. Our main technical contribution is a quantum-succinct \emph{claw-state generation} protocol that allows us to bootstrap a small...

Low-Weight Canonical Logical Bases from Pair-Partition CodesTier 3

We construct complete canonical logical bases for qubit CSS codes by assigning quaternary coefficients to binary circulant permutation matrix pair-partition (CPM-PP) checks, constructing and normalizing logical representatives, and expanding the result into binary matrices. When the two check systems have invertible submatrices on disjoint column sets, cofactor representativ...

Exponential lower bounds for low-degree strategies in position-based quantum cryptographyTier 3

Non-local quantum computation (NLQC) consists on the implementation of a bipartite unitary U_(AB) by two cooperating distant players by means of a two-round protocol with a single intermediate round of simultaneous communication. It is a major open question to know whether there exists a unitary U_(AB) whose implementation in NLQC requires extra quantum systems with dime...

Quantum Query Complexity Beyond the Worst CaseTier 3

Smoothed analysis is a central framework in classical algorithms for explaining the performance of algorithms beyond the worst case, often explaining why algorithms perform well in practice. We initiate a systematic study of its quantum counterpart and show the following results. (1) We show that there is a total function whose smoothed quantum query complexity is exponent...

Sublinear Copies Suffice for Fidelity Estimation with Pauli MeasurementsTier 3

We present a protocol that estimates the quantum fidelity, up to precision ε, between a known target state and unknown lab-prepared state with sublinear, o(d^(0.9908)/ε^2), number of Pauli basis measurements.

Induced Coherence in Quantum and Classical Interferometry: Origin and ControlTier 3

The wave-particle duality that manifests in the Young's double-slit interferometry satisfying the well known Englert-Greenberger-Yasin inequality has recently been shown to obey a universal triality relation involving coherence, predictability and rather surprisingly entanglement. In the present work, we explicitly demonstrate the persistence of the triality relation in the...

How fast can a parent estimate the value of their children? A quantum algorithm for stochastic gamesTier 3

We give a quantum algorithm for stochastic $2-player games. Their game trees are the expectiminimax trees of classical game search: m adversarial layers alternate with m chance layers, every node has deg children, and the leaf values lie in an interval of length N. The algorithm estimates the value of the game to root mean square error ε with [ O( K^D ...

Electron decoherence in cylindrical holes and circular aperturesTier 3

The coherence of free electrons sets fundamental limits on the resolution and contrast of phase-sensitive electron microscopy because coherence is lost whenever the electron leaves a distinguishing excitation in its environment. We develop a quantitative theory of fast-electron decoherence in two canonical geometries: a cylindrical hole drilled through a realistic metal and...

Temporal trade-offs in high-dimensional entanglement: a comprehensive noise model for optimal time-bin QKD protocolsTier 3

High-dimensional time-bin entanglement is known for having high potential for quantum key distribution (QKD) applications, being easily implementable, robust and may offer better keyrates than simple qubit protocols. The temporal encoding, combined with limited clock resolution, however, implies a trade-off: Is it better to send more low-dimensionally encoded photons or few...

Efficient classical algorithm for estimating linear statistics of Boson SamplingTier 3

Boson Sampling is a prominent candidate for the demonstration of quantum computational advantage but it remains unclear whether a large-scale boson sampler can find useful computational applications. The challenge is that to use a boson sampler to estimate, for example, a physical observable, it is necessary to coarse grain the outcome distribution, owing to the exponential...

Fixed-Time Gaussian State Transfer via Collective Dissipation in a Fully Static ArchitectureTier 3

We establish a fully static, dissipation-only primitive for Gaussian state transfer in which collective coupling to a shared environment fixes a single transfer time without coherent transport or time-dependent control. The dynamics close in a bright--dark decomposition, yielding an analytic transfer time t^* = π/ g_a and a real interference factor that eliminates dyna...

Heuristic lower bounds on real Grothendieck constants of finite and infinite orderTier 3

We propose candidate lower bounds on the real Grothendieck constants K_G(d) and their infinite-dimensional limit K_G using rotationally invariant cubic kernels. For the continuous construction, we identify an explicit threshold above which hemispherical binary strategies are unstable under cubic boundary deformations. Supported by numerical evidence,...

Distributional Variants of the Aaronson-Ambainis ConjectureTier 3

A longstanding conjecture in quantum complexity theory asserts that, under the uniform input distribution, quantum query algorithms can be polynomially simulated by classical query algorithms. More precisely, the acceptance probability of any quantum query algorithm can be approximated, on average over uniformly random inputs, by a classical query algorithm, with only polyno...

Generalized LIMDDs: Succinctness and Canonicity for Decision Diagrams Modulo a GroupTier 3

A reduced ordered decision diagram is the minimal automaton of a function on words of fixed length: its nodes are the residuals, and reduction is the Myhill--Nerode quotient. We study what happens when that quotient is coarsened by a group. Fix a group G acting on residuals, merge two nodes when their residuals lie in one G-orbit, and record the group element on the edge...

Gauge freedom and efficient algorithms for Lindbladian learningTier 3

We study the problem of learning a local Lindbladian in the presence of state-preparation-and-measurement (SPAM) noise. Although recent work has developed scalable learning algorithms under idealized access assumptions, SPAM can make distinct Lindbladians experimentally indistinguishable, thus making part of the Lindbladian fundamentally unlearnable. We give a sharp characte...

Exact probability distributions of complex spacing ratios in non-Hermitian random matricesTier 3

The complex spacing ratio is the complex displacement from a reference eigenvalue to its nearest neighbor divided by the corresponding displacement to its next-to-nearest neighbor. Its statistics provide a useful diagnostic of spectral correlations and nonintegrability in open quantum systems. Here, starting from the exact joint eigenvalue probability densities, we derive fi...

Weakly interacting fermionic Gibbs states are Gaussian mixtures and classically simulableTier 3

Identifying regimes in which interacting fermionic systems admit efficient classical simulation is a crucial task in quantum many-body physics. In this work, we rigorously establish the Gaussianity and classical simulability of sufficiently weakly interacting fermions. For the Gibbs state of a local interacting fermionic Hamiltonian H=H_0+V at any finite temperature and in...

The Overlap Gap Property: Separating Quantum and Quantum-Inspired Approximate Optimization AlgorithmsTier 3

In this paper, we prove that the Mean-Field Approximate Optimization Algorithm (MF-AOA), a quantum-inspired classical algorithm of the Quantum Approximate Optimization Algorithm (QAOA), is unable to give arbitrary near optimal solution for problems exhibiting the Overlap Gap Property (OGP). We show this by relating the MF-AOA to finite-memory Approximate Message Passing (AMP...

Accurate and bounded approximation of quantum correlation functionsTier 3

The exact classical simulation of non-integrable quantum systems rapidly becomes intractable beyond small system sizes, yet its role is central to predicting many-body dynamics. Approximate methods alleviate this cost but typically lack rigorous guarantees on their deviation from the exact result. For the infinite-temperature correlation function, we derive a rigorous error...

From Quantum to Classical Dissipative Spin DynamicsTier 3

The Landau-Lifshitz-Gilbert (LLG) equation provides the fundamental description of dissipative magnetization dynamics. A recently proposed quantum analog, the quantum Landau-Lifshitz-Gilbert (QLLG) equation, extends this framework to quantum spin systems. However, whether the QLLG equation recovers the LLG equation in the classical large-spin limit for interacting spin syste...

Cyclotomic Cosets: Hidden Subgroup and Quantum Sieving Algorithm for Prime-Power ModuliTier 3

The Learning With Errors (LWE) problem is a fundamental assumption in post-quantum cryptography. Regev established a quantum reduction from LWE to the Dihedral Coset Problem (DCP). Later, Brakerski et al. introduced the Extrapolated Dihedral Coset Problem (EDCP), proving its equivalence to LWE. However, unlike DCP, EDCP no longer admits a coset structure. This limits the dir...

Donate & Join Us! Trick, Treat, and Quantum Physics: Kai Brings Halloween to ETH ZürichTier 2

Insider Brief Halloween is just around the corner – and at ETH Zürich this year it’ll be blended with quantum physics! On October 31, 10-year-old Kai will take the stage at wow² Space dressed as the Grim Reaper, ready to ask some of the biggest questions in science in the way only a 10-year-old can. […]

India’s Finance Minister Places Quantum Among Next Major Infrastructure Investment PrioritiesTier 2

Insider Brief India’s next major infrastructure investments will include quantum technology alongside artificial intelligence and semiconductor chips, Finance Minister Nirmala Sitharaman said, according to the Hindustan Times. Speaking at a fireside chat organized by the IIT Madras Alumni Association, Sitharaman called for academia and industry to work together to build capa...

Researchers Identify Limits on Quantum Battery Energy And Power StabilityTier 2

Insider Brief PRESS RELEASE — New research identifies fundamental limits on the reliability of quantum batteries and shows how charging strategies can balance high power with stable energy and power delivery. The findings represent an important step toward the future development of practical and useful quantum energy-storage devices. Quantum uncertainty sets a fundamen...

Zero Knowledge Proofs in Quantum NetworksTier 3

Zero-knowledge proofs (ZKPs) enable the verification of a statement without revealing any information beyond its validity and constitute a fundamental primitive in cryptography and information theory. However, existing constructions rely on computational assumptions and are predominantly confined to bipartite settings, leaving their information-theoretic realization in bipar...