September 30, 2026

Infleqtion and Riverlane Execute Strategic MOU to Integrate Neutral-Atom Hardware with Real-Time QEC DecodersTier 2

Infleqtion and Riverlane have partnered to integrate real-time quantum error correction with neutral-atom hardware. This collaboration aims to close the latency gap in qubit error detection and processing, enabling scalable logical qubits. They will combine Infleqtion's neutral-atom QPU and qLDPC software with Riverlane's Deltaflow decoding platform to run dynamic error c...

Adaptive decoding of quantum LDPC codes through decoder disagreementTier 3

Accurate decoding of quantum low-density parity-check (qLDPC) codes often relies on expensive post-processing search, although decoding difficulty varies strongly between syndromes. We find that the benefit of deeper post-processing search is highly concentrated in a small subset of decoding instances, and that these instances can be identified directly from the decoder itse...

Parametric DRAG for leakage-suppressed exchange gates in superconducting qubitsTier 3

Programmable exchange interactions support quantum gates and many-body simulation in superconducting circuits. Fast excitation transfer, however, opens two leakage pathways in weakly anharmonic transmons, degrading gates and driving simulated dynamics outside the encoded state space. We introduce parametric derivative removal by adiabatic gate (PDRAG) to suppress both pathwa...

Xanadu and Bluefors Form Multi-Million Dollar Strategic Partnership to Develop Modular Cryogenic Infrastructure for Utility-Scale Quantum Data CentersTier 2

Xanadu and Bluefors have formed a multi-million dollar partnership to develop a modular cryogenic infrastructure for utility-scale quantum data centers. Their joint effort focuses on replacing large, centralized cryoplants with compact, mass-manufacturable cryogenic modules designed for high-density detector arrays operating near 2 Kelvin. This collaboration aims to addre...

Previously: 2026-09-01

When Classical Correlations Certify Entanglement RecoveryTier 3

Entanglement and state distinguishability have long been central topics in quantum foundations. While each has developed into a rich subject in its own right, they can be connected through measurements in complementary bases. This connection provides insights into quantum and classical correlations and underlies many information-processing tasks, most notably quantum error c...

A Neutral Atom-Based Hybrid Classical-Quantum Approach for the Entanglement Routing ProblemTier 3

Efficient end-to-end entanglement distribution in quantum information networks requires routing under limited resources and fidelity constraints. We study entanglement routing as a fidelity-constrained unsplittable multicommodity flow problem that maximizes the number of admitted requests. As a proof of concept, we integrate neutral-atom quantum optimization into a hybrid cl...

Spin-exchange interactions between circular Rydberg atoms over long timesTier 3

Arrays of neutral atoms excited to Rydberg levels have emerged as one of the most promising platforms for quantum computation and simulation. With the hope to outperform classical devices, the number of atoms has been increased by orders of magnitude. However, the interaction time, i.e., the maximum accumulated time during which an atom interacts with its neighbours, has bee...

Optical Fourier Architecture for Universal Nonlinear FunctionsTier 3

We introduce an exact algebraic architecture that evaluates an arbitrary finite Fourier series using a two-mode (2 ×2) linear optical circuit, with the only tunable components being single-mode phase shifters encoding the function argument. We prove that such a circuit must exist for every Fourier series and derive an analytical method for its construction based on s...

Foundation Neural-Network Quantum States for Molecular Potential Energy Surfaces in Second QuantizationTier 3

Second-quantized neural-network quantum states have achieved accurate molecular energies, but extending them across molecular geometries requires a shared representation of the geometry-dependent wavefunction coefficients. We introduce geometry-conditioned foundation neural-network quantum states for molecular electronic structure in second quantization. A single autoregress...

Digital quantum state preparation by nucleationTier 3

Quantum state preparation is crucial for quantum algorithms, and improved state preparation methods can reduce resource requirements by orders of magnitude. In this work, we introduce a state preparation method for lattice Hamiltonians on digital quantum computers inspired by nucleation. In our method, the exact ground state of a small lattice Hamiltonian is prepared in a qu...

UC Santa Barbara Researchers Join Three NSF Quantum Leap Challenge Institutes Under $290 Million Portfolio RenewalTier 2

UCSB faculty will participate in three NSF Quantum Leap Challenge Institutes (QLCI), sharing $290 million in renewed and new funding. This initiative, under the National Quantum Initiative Act, focuses on accelerating quantum research into manufacturing by integrating academic researchers with national laboratories and private industry. The QLCI program also aims to devel...

Roadrunner Quantum Lab Opens 35,000-Square-Foot Albuquerque Facility with Initial Cohort of Quantum Startups, National Labs, and Ecosystem PartnersTier 2

The Roadrunner Quantum Lab (RQL) has opened a 35,000-square-foot facility in Albuquerque, New Mexico, serving as a hub for quantum technology testing and commercialization. Supported by $25 million in state funding, it houses 15 quantum hardware, software, sensing, and capital partners, facilitating the transition of quantum physics research into commercial hardware. The...

Royal Bank of Canada Launches Enterprise Quantum Strategy and Academic Workforce PipelinesTier 2

Royal Bank of Canada (RBC) has launched a multi-year enterprise quantum strategy focusing on internal R&D, post-quantum cybersecurity, academic partnerships, and hardware investments. This initiative includes collaborations with Xanadu, the University of Waterloo, and the University of Toronto to develop quantum applications for financial modeling, optimize portfolio...

Cloudflare Launches Public Certificate Authority to Secure the Web Against Quantum ThreatsTier 2

Cloudflare is becoming a public Certificate Authority (CA) to secure the web against quantum threats by introducing an open, automated, and high-scale issuance service. This initiative will provide both classical TLS certificates and next-generation Merkle Tree Certificates (MTCs) to prevent widespread web outages and combat "harvest now, decrypt later" adversary campaign...

Cloudflare Plans Public Certificate Authority for Post-Quantum SecurityTier 2

Insider Brief PRESS RELEASE — Cloudflare, Inc. (NYSE: NET), the leading connectivity cloud company, today announced its intent to become a public Certificate Authority (CA), an open service that issues the digital certificates websites need to encrypt traffic and prove their identity to visitors. The new CA will support both traditional encryption and next-generation p...

NATO Sets Quantum Roadmap For Military Trials And Secure CommunicationsTier 2

Insider Brief NATO has set deadlines for testing quantum technologies in military operations and strengthening its defenses against quantum threats, turning its research ambitions into a schedule of trials, assessments and security projects. The alliance’s new Quantum Technology Roadmap calls for sea trials of quantum sensors in 2026 and 2027, an initial report on military [...

French National Quantum Update: September 2026Tier 2

Executive Summary The summer break is definitely over. France’s quantum sector focused on the manufacturing, software and commercial relationships needed to put quantum computers into wider use in September 2026. Quobly reported progress on chips made through an industrial semiconductor process, while Alice & Bob and Quandela outlined efforts to connect quantum processor...

Query-optimal unitary channel tomography in diamond distance with parallel accessTier 3

In the study of quantum process tomography, it has remained open how to learn a unitary channel in diamond distance with strictly parallel queries as efficiently as with sequential queries. Sequential queries allow one to exploit adaptivity to refine the estimate and adjust the learning strategy accordingly, whereas such adjustments are impossible for parallel queries. From...

The exact strong converse exponent for private communication over quantum channelsTier 3

We determine the exact strong converse exponent for secret-key transmission and generation over general finite-dimensional quantum wiretap channels, measuring reliability and secrecy jointly by squared fidelity to an ideal secret key. We introduce a novel Renyi private information whose regularization characterizes this exponent. An exact integral representation in terms of...

Resource Compatibility in Optimal Quantum Symmetry TestingTier 3

Can a symmetry be tested optimally without using the quantum resource naturally associated with it? For parallel subgroup-versus-Haar testing, we derive a quantitative representation-theoretic converse for every protocol with zero type-I error: the excess type-II error is bounded below by the sum of two nonnegative penalties, one for weight on suboptimal subgroup types and o...

Multimode radiation pressure actuation of a mechanical resonator using a spatial mode sorterTier 3

Multimode optomechanical scattering is ubiquitous in free-space imaging protocols, but its radiation pressure counterpart is challenging to detect with extended objects. Here we demonstrate radiation pressure actuation of a nanomechanical membrane using dynamically structured light from a spatial mode demultiplexer (SPADE). Using single- and two-mode illumination, we directl...

The Principle of Minimum Justified CorrelationTier 3

It is shown that Shannon entropy, Fisher information, and quantum-mechanical kinetic energy may all be viewed as measures of correlation. We begin with a fundamental correlation-destroying map: a joint probability density ρ(x,y) is replaced by ρ_x(x)ρ_y(y), the product of its marginal distributions. In the discrete case, Shannon's entropy is nondecreasing under this map....

Learning quantum symmetriesTier 3

Quantum algorithms are powerful tools for finding symmetries of classical objects, most famously through Shor's algorithm and the framework of the Hidden Subgroup Problem (HSP). In this work, we study quantum algorithms for learning symmetries of quantum objects. Our starting point is the recently introduced State Hidden Subgroup Problem (StateHSP), a quantum generalisation...

A commuting operator self-test for exact entanglement embezzlementTier 3

We show that the optimal commuting operator correlation for a variant of Coladangelo's two-player generalized nonlocal game, based on the embezzlement of entanglement, is a commuting operator self-test. Our result gives the first correlation self-test for an exact entanglement embezzlement protocol in the commuting operator framework. Because the unique optimal correlation n...

Ramanujan quantum expanders from the Weil representationTier 3

For every odd prime power q and D=q+1, we construct an infinite family of Ramanujan quantum expanders of degree D. The construction transfers Morgenstern's Ramanujan Cayley graphs on PSL_2(F_p) for p which is an even power of q, through the odd irreducible subrepresentation of the Weil representation of SL_2(F_(p...)

Classical Verification of Quantum Computation with Quasilinear Resources, from Compiled Nonlocal GamesTier 3

Computational self-testing gives a classical verifier command over the quantum register of a single computationally bounded prover. We use this framework to construct the first argument system for BQP with quasilinear total resource requirements in the circuit model. Our argument system is based on the learning with errors (LWE) assumption and requires total resources of $O(...

A Tale of Two Walks: Kipnis, Marchioro and Presutti Meet Kac in a Quantum WorldTier 3

We reveal an unexpected connection between the parallel Kac's walk and the Kipnis-Marchioro-Presutti (KMP) process. The twirling channel induced by the parallel Kac's walk on the symmetric subspace is exactly encoded by a classical Markov chain on partitions, which lifts to a parallel KMP process on complete graphs. This correspondence reduces the analysis of the twirling ch...

Density Matrices of Pulsed Quantum LightTier 3

Pulsed light is represented by density matrices whose correlation functions have different properties of stationarity and coherence. We show that these density matrices yield equivalent measurement results after accounting for finite detection times. This in turn reveals a physical meaning to the length of a quantization cavity and explains the origin of the physical spectru...

Improved estimate of local Markovianity for quantum Gibbs statesTier 3

We establish improved locally Markovian properties of quantum Gibbs states at every fixed positive temperature. For finite-range interactions of bounded interaction degree, the conditional mutual information (CMI) decays exponentially with separation, with a prefactor exponential in the boundary size. This improves the exponential volume dependence of the local Markov bounds...

Rapid Mixing of Parallel Kac's Walk: From Spheres to Stiefel ManifoldsTier 3

Kac's walk is a classical local random walk whose action on a single real unit vector in dimension d mixes in total variation in Θ(dlog d) sequential steps~\cite{PS17}. Lu, Qin, Song, Yao, and Zhao introduced a parallel version of Kac's walk that mixes a single quantum state in O(log d) rounds~\cite{LQSY+26}. After discretizing the randomness and replacing it by suit...

Strong-to-Weak Spontaneous Symmetry Breaking of Dephased FermionsTier 3

Strong-to-weak spontaneous symmetry breaking (SWSSB) is a novel phase transition in mixed states associated with the loss of global charge information. In this work we study fermions with U(1) symmetry under infinite density dephasing and derive the SWSSB properties of the resulting mixed states. Our central observation is that at infinite dephasing every Renyi correlator...

Optimal Quantum Junta Testing without Inverse QueriesTier 3

We study the query complexity of testing quantum juntas. Given an unknown n-qubit unitary or quantum channel, the goal is to decide whether it acts nontrivially on at most k qubits or is ε-far from every such operation. For unitaries, we consider the forward-only model, where the tester has access to U, but not to U^† or controlled-U. We give tigh...

Towards verifiable quantum advantage with random circuits: Observables that survive concentrationTier 3

Demonstrating quantum advantage on current quantum hardware is a central goal of quantum computing, and random quantum circuits underpin many leading proposals. Yet sampling-based demonstrations are often difficult to verify, while observable-based approaches face a different challenge: concentration can suppress differences between circuit instances. Recent experiments have...

Attosecond correlation interferometryTier 3

Correlations between optical modes, ranging from classical fluctuations to quantum entanglement, are a cornerstone of modern optics and emerging quantum technologies. However, probing these correlations on the natural timescale of electronic motion - the attosecond regime - remains a major challenge. Here, we generate and characterize correlated attosecond extreme-ultraviole...

Measuring the spin of a spin-1/2 and getting a result of 7Tier 3

The weak value of an operator is the average result of measuring that operator on a quantum system given specified initial and final states. The overlap between these states appears in the denominator of the weak value, and thus if that overlap is small, the weak value can be arbitrarily large. In 1988, Albert, Aharonov, and Vaidman proposed a weak Stern-Gerlach experiment w...

Quantum Complexity of Ancilla-Free Unitary Embeddings for Nonlinear Dynamics via Generalized State-Dependent Double-Bracket FlowsTier 3

Simulating nonlinear dynamics with quantum computers has gained increasing attention. In general, such simulations require additional quantum resources because unitary quantum evolution is linear. A fundamental question is how nonlinear dynamics can be embedded into fully coherent, ancilla-free unitary circuits and how the complexity of the dynamics governs the required quan...

Optimal single-copy estimation of quantum state moments: why Tr(ρ^3) and Tr(ρ^4) are equally hardTier 3

Estimating nonlinear properties of an unknown quantum state with restrictive experimental accessibility is a fundamental problem in quantum learning. We study the sample complexity of estimating the state moments Tr(ρ^t), allowing arbitrary adaptive single-copy measurements. While purity estimation has optimal sample complexity Θ(√d) at constant addit...

Multistate Torsion in ZitterbewegungTier 3

We derive nonlinear Zitterbewegung velocity of electrons augmented by band torsion in crystals. The equation of motion with multistate quantum geometric tensors and torsion culminates in transient nonlinear photocurrent responses distinct from the recently measured resonant steady-state photovoltaic effects induced by circularly polarized light. Tomography protocols for meas...

Resonance Breaking in Noisy Shor's AlgorithmTier 3

We argue that the exponential quantum advantage in Shor's algorithm is broken under one-layer depolarizing noise of arbitrary small error rate, by analyzing a resonance breaking phenomenon in noisy quantum circuits. First, we express the distribution of measurements on n-qubit strings as the superposition of the 4^n wave functions in the Pauli path integral. In the noise...

Semiclassical spin-bath calculation of the nitrogen-isotope effect on NV^- ensemble coherence in diamondTier 3

The ratio T_2/T_2^* of the Hahn-echo and Ramsey times of nitrogen-vacancy (NV^-) ensembles is independent of the nitrogen concentration [N] and is ≈ 16 in diamond of natural isotopic abundance (^(14)N), yet a recent ^(15)N-doped ensemble magnetometer gives only 8.05 ± 0.18 in the single-quantum convention. We ask whether the nitrogen nuclear isotope alo...

Quantum Statistical Thermal Engine at the BCS-BEC crossoverTier 3

We propose a quantum heat engine based on a two-component Fermi gas with s-wave contact interaction, operating across the BCS-BEC crossover. The work is extracted from the statistical properties of the gas, which are controlled by the interaction, rather than relying solely on compression and expansion stages. Using the functional renormalization group formalism, we obtain t...

Asymptotic Pseudospectra in Dissipative Floquet Quantum Systems: Geometric Structures and Observable DynamicsTier 3

In periodically driven open quantum systems, nonnormality renders the Floquet spectrum insufficient as the system approaches the thermodynamic limit, so that pseudospectra are needed to characterize the dynamics accurately. While conventional approaches mainly focus on the local dynamics of isolated pseudospectra, their global connections and the resulting physical consequen...

Multi-Parameter Error Mitigation in Parametric Down-Conversion via SU(1, 1) Composite SegmentationTier 3

Spontaneous parametric down-conversion is a primary resource for generating non-classical light, yet phase mismatch fluctuations from temperature drift, angular misalignment, and domain fabrication errors reduce pair-generation efficiency and phase stability. Here, we analyze error mitigation in spontaneous parametric down-conversion using composite segmentation governed by...

Exact anomalous current fluctuations in the strong-anisotropy limit of the XXZ chainTier 3

We study spin-current fluctuations of the folded XXZ chain, which describes the strong-anisotropy limit of the XXZ chain. We obtain an exact expression for the moment-generating function of the time-integrated spin current at infinite temperature. A long-time asymptotic analysis establishes that the rescaled time-integrated current converges to a non-Gaussian distribution de...

Experimental certification of multipartite Bell correlations using only few-body symmetric correlationsTier 3

Certifying Bell correlations in increasingly larger multipartite quantum systems is challenging because conventional Bell inequalities rely on many-body correlations, which become experimentally demanding to estimate as system size grows. Here we demonstrate that multipartite Bell correlations can be certified using few-body permutation-invariant (PI) correlations with a fix...

Succinct Arguments for QMA in the Quantum Random Oracle ModelTier 3

Succinct arguments are a fundamental cryptographic primitive for verifying computational claims with small communication. In the classical setting, succinct arguments for NP can be constructed from unstructured hardness alone (e.g., hash functions) by compiling probabilistically checkable proofs (PCPs) or interactive oracle proofs (IOPs) for NP via the commit-and-open paradi...

Consistent histories and the ultrametric on infinite tensor productsTier 3

The consistent histories formulation of quantum mechanics assigns classical probabilities to sequences of coarse-grained events when the corresponding interference terms vanish. In finite models these terms generically need not vanish exactly, and their smallness alone supplies no asymptotic geometry on the space of histories. We construct such a geometry for histories that...

A magnetic-field insensitive gate set for trapped-ion nuclear spin qubitsTier 3

We outline a complete set of operations for manipulating nuclear spin qubits of trapped-ions stored in high magnetic fields such as required for Penning trapping, where the nuclear and electron spins are largely decoupled due to the dominance of the external field Hamiltonian. The reduced nuclear magnetic moment results in insensitivity to external magnetic fields compared t...

Scanless quantum Fourier-transform mid-infrared spectroscopy for solids and surface analysisTier 3

Quantum infrared (IR) spectroscopy is a novel technique based on nonlinear interferometry and quantum sensing with undetected photons. In this approach, spectrally far-separated correlated photon pairs are used for detection and probing, respectively. Hence, the probing wavelength domain (mid-IR) is substantially different from the detection spectral range (near-IR), which e...

NSF Awards $600,000 to Stony Brook and University of Hawaiʻi to Advance Distributed Quantum Intelligent Sensor NetworksTier 2

Researchers at Stony Brook University and the University of Hawaiʻi at Mānoa have been awarded a $600,000 NSF grant to develop Quantum Intelligent Sensor Networks (QISNs). This project aims to advance quantum metrology by engineering distributed, entangled sensor nodes that work together as a coordinated system, rather than optimizing single isolated sensors. The research...

Project Eleven Acquires Riva Labs to Scale Post-Quantum Cryptography and Blockchain Infrastructure StackTier 2

Project Eleven has acquired Riva Labs to create a comprehensive post-quantum cryptography and blockchain infrastructure. This merger addresses vulnerabilities in current public-key cryptography by integrating quantum-resistant solutions directly into the technology stack. The combined entity will focus on developing agile post-quantum migration frameworks, utilizing AI-dr...

New Quantum Algorithm Targets Bottleneck in Fluid-Flow ModelingTier 2

Insider Brief PRESS RELEASE — Researchers at the Department of Energy’s Oak Ridge National Laboratory used the world’s fastest supercomputer for open science to develop a quantum algorithm that could lead to more advanced models in fluid dynamics and other scientific fields. The results of the study, supported by the Oak Ridge Leadership Computing Facility’s...

Roadrunner Quantum Lab to Open Its Doors in Albuquerque With First Eleven TenantsTier 2

Insider Brief PRESS RELEASE — Roadrunner Venture Studios and New Mexico’s Technology and Innovation Office (TIO) today debuted the Roadrunner Quantum Lab (RQL) Powered by the State of New Mexico. Built in Albuquerque’s Innovation District, the new 35,000-square-foot will be an anchor facility for New Mexico’s $450M commitment to quantum, granting essential access to fo...

Project Eleven Acquires Riva Labs for Post-Quantum SecurityTier 2

Insider Brief PRESS RELEASE — Project Eleven, the company building post-quantum security infrastructure for digital assets, today announced its acquisition of Riva Labs, expanding its expertise in post-quantum signatures, wallets, MPC, and account abstraction. The acquisition also brings technology and intellectual property developed through Riva’s work across Et...

Quantum Computing Explained – With Maple Syrup and SunglassesTier 2

The Insider Brief: A quantum computer is being tuned with maple syrup. Not metaphorically – actually. That’s the answer Ghislain Lefebvre, interim executive director of Institut quantique at Université de Sherbrooke, gives when asked the deliberately odd question that opens this episode of Kai Asks: what does maple syrup have to do with building a […]

U.S., Europe Need Closer Cooperation to Build Quantum Industry, QED-C Official SaysTier 2

Insider Brief National, state and regional efforts to build quantum industries often capture the headlines. But the strengths that reach across those borders may prove to be just as important to their success, according to a senior industry consortium official writes in EE Times. According to Jonathan Felbinger, deputy director of the Quantum Economic Development […]

Optimal Ground-State Preparation with a Guiding StateTier 3

Suppose a Hamiltonian H has a unique ground state |ψ_0⟩ with an eigenvalue E_0, and we have an estimate E_0 such that |E_0-E_0|≤δ, and there is a gap of at least 3δ between E_0 and all other eigenvalues. Suppose we have a unitary A available that can produce a "guiding state'" A|0⟩ that has overlap at least γ with |ψ_0rang...

Optimal Quantum-Classical Separations for Exact LearningTier 3

We study exact learning with membership queries for concept classes C⊆{0,1}^N, focusing on the relationships among their deterministic, randomized, and quantum query complexities, denoted D(C), R(C), and Q(C), respectively. The two canonical quantum speedups in this model are witnessed by Grover...

Local autonomous inference machines for quantum LDPC codesTier 3

We introduce a local and distributed framework for decoding quantum LDPC codes. Built atop belief propagation (BP), the architecture combines strictly local processing of syndrome information, local feedback, autonomous operation, and highly parallelized decoding. We establish the framework at two complementary levels. First, we show that any code exhibiting a threshold unde...

Optimal Tolerant Testing of Lindbladian DissipationTier 3

Quantifying dissipation is essential for controlling quantum noise and characterizing open-system dynamics. In practical experimental settings, residual noise may still persist despite efforts to suppress it, making it important to determine whether the dissipative strength remains within a prescribed tolerance threshold. We study this question for an unknown, time-independe...