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Quantum Error Correction: Surface Code & Fault-Tolerant Computing

Quantum error correction news: logical qubits, surface code, fault-tolerant quantum computing, QEC. Error mitigation & suppression.

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Quantum error correction (QEC) is the critical enabler for fault-tolerant quantum computing, protecting quantum information from environmental noise through redundant encoding across multiple physical qubits. Recent breakthroughs demonstrated below-threshold error correction where logical qubit error rates fall below physical qubit rates.

The 2D surface code is the leading QEC approach due to high error threshold (~1%), local nearest-neighbor interactions, and compatibility with superconducting chip designs. Recent breakthroughs include Google's Willow demonstrating below-threshold surface code scaling, and IBM's Heavy Hex optimizing qubit connectivity for surface code implementation.

India's Quantum Error Correction Research

India's National Quantum Mission includes quantum error correction in its basic science research component. The Foundation for QC Innovation at IISc Bengaluru addresses error correction as part of its quantum computing development. The Harish-Chandra Research Institute (HRI) and Institute of Mathematical Sciences (IMSc) conduct theoretical research on quantum error correction codes.

The NQM targets developing intermediate-scale quantum computers with 50-1000 physical qubits, requiring error mitigation and eventually error correction to achieve quantum advantage. The mission includes development of indigenous control electronics and error mitigation techniques.

Scientists Propose More Realistic Benchmarks For Quantum Algorithms - The Quantum Insiderquantum-computing

Scientists Propose More Realistic Benchmarks For Quantum Algorithms - The Quantum Insider

Scientists Propose More Realistic Benchmarks For Quantum Algorithms The Quantum Insider

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A Quantum Optimization Framework for Data-Assimilation-Augmented Parameter Estimationquantum-computing

A Quantum Optimization Framework for Data-Assimilation-Augmented Parameter Estimation

--> Quantum Physics arXiv:2608.13614 (quant-ph) [Submitted on 12 Aug 2026] Title:A Quantum Optimization Framework for Data-Assimilation-Augmented Parameter Estimation Authors:Muhammad Jalil Ahmad, Mohammadhossein Mohammadisiahroudi, Animikh Biswas, Kathleen Hoffman View a PDF of the paper titled A Quantum Optimization Framework for Data-Assimilation-Augmented Parameter Estimation, by Muhammad Jalil Ahmad and 3 other authors View PDF HTML (experimental) Abstract:Parameter estimation is a fundamental challenge in the calibration of ordinary differential equation (ODE) models, where repeated numerical integration can lead to high computational cost. In this work, we investigate whether quantum algorithms can be leveraged to assist parameter estimation in nonlinear dynamical systems. We develop a hybrid classical-quantum framework that reformulates a data-assimilation-augmented parameter estimation problem as a combinatorial optimization task. Model dynamics and data assimilation are enforced entirely on the classical side, while the resulting parameter estimation cost functional is discretized and approximated by a quadratic unconstrained binary optimization (QUBO) surrogate. This surrogate is mapped to an Ising Hamiltonian, and quantum optimizers are used to search for low-energy configurations corresponding to candidate parameter estimates. We apply the framework to SIS and SIR epidemic models, the chaotic Lorenz-63 system, and a high-dimensional two-layer Lorenz-96 system. In this setting, the method is used to recover classical system parameters from partial state observations across steady-state, chaotic, and high-dimensional multiscale dynamical systems. Numerical experiments with synthetic data show that the proposed approach accurately recovers parameters while requiring data-assimilation solves only on a prescribed coarse grid. The framework avoids quantum state tomography, illustrating a viable pathway for integrating quantum optimization into data-driven par

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A scalable edge-pass Purcell filter for high-fidelity readout of superconducting qubitsquantum-computing

A scalable edge-pass Purcell filter for high-fidelity readout of superconducting qubits

--> Quantum Physics arXiv:2608.13627 (quant-ph) [Submitted on 13 Aug 2026] Title:A scalable edge-pass Purcell filter for high-fidelity readout of superconducting qubits Authors:Xudong Liao, Yuan Li, Sainan Huai, Shuyi Pan, Zhenxing Zhang, Zhiwen Zong, Kunliang Bu, Yulei Ye, Wen Zheng, Xinsheng Tan, Yang Yu, Xiaopei Yang, Tianqi Cai, Shengyu Zhang View a PDF of the paper titled A scalable edge-pass Purcell filter for high-fidelity readout of superconducting qubits, by Xudong Liao and 13 other authors View PDF HTML (experimental) Abstract:High-fidelity readout with strong Purcell protection of qubit coherence is essential for scalable superconducting quantum processors, yet the finite passband and sizable footprint of conventional band-pass Purcell filters make them hard to scale. Here we introduce a scalable edge-pass Purcell filter that separates the readout band from the protected qubit band by a single transmission edge, freeing the readout resonators from bandwidth constraint. Depending on whether the transmitting band lies above or below the cutoff, the compact network is realized as a high-pass filter (HPF) or a low-pass filter (LPF). The HPF reaches an average readout fidelity of 99.46(4)% (up to 99.56%) with a 150-ns pulse, and the LPF reaches 99.49(3)% (up to 99.57%) with a 130-ns pulse. The average single-qubit gate fidelities are 99.94% (HPF) and 99.93% (LPF). Relative to the filter-free Purcell limit, the filters substantially extend the qubit lifetime, and the Purcell protection deepens at higher filter order. In addition, an intrinsic dissipation mode of the filter offers a qubit-reset channel. This leads to a compact architecture that unifies fast, high-fidelity readout, Purcell protection, and effective reset within a single filter for large-scale fault-tolerant quantum computation. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.13627 [quant-ph]   (or arXiv:2608.13627v1 [quant-ph] for this version)   https://doi.org/10.48

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Heuristic Lookahead Distillation Protocol Searchquantum-computing

Heuristic Lookahead Distillation Protocol Search

--> Quantum Physics arXiv:2608.13644 (quant-ph) [Submitted on 13 Aug 2026] Title:Heuristic Lookahead Distillation Protocol Search Authors:Matthew Barber, Stefano Pirandola View a PDF of the paper titled Heuristic Lookahead Distillation Protocol Search, by Matthew Barber and 1 other authors View PDF HTML (experimental) Abstract:Bipartite qubit entanglement distillation is the process of converting noisy ebits into pure ebits using only local operations and classical communication. This is a core operation for quantum repeaters, enabling such crucial tasks as long-distance quantum communication and distributed quantum computing. In this work, we introduce a method for searching for entanglement distillation protocols and, using this technique, distil qubit Werner states at a higher rate than could be achieved using previously discovered protocols. In particular, we demonstrate the advantage of our new distillation strategy by improving the best-known lower bound for the two-way-assisted quantum capacity of the qubit depolarising channel across a wide range of channel parameters, making progress in one of the long-standing problems of quantum information theory. Comments: Subjects: Quantum Physics (quant-ph); Other Condensed Matter (cond-mat.other); Mathematical Physics (math-ph); Optics (physics.optics) Cite as: arXiv:2608.13644 [quant-ph]   (or arXiv:2608.13644v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.13644 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Stefano Pirandola [view email] [v1] Thu, 13 Aug 2026 18:00:02 UTC (368 KB) Full-text links: Access Paper: View a PDF of the paper titled Heuristic Lookahead Distillation Protocol Search, by Matthew Barber and 1 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-08 Change to browse by: cond-mat cond-mat.other math math-ph

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Entanglement Negativity in Noisy Quantum Volume Samplingquantum-computing

Entanglement Negativity in Noisy Quantum Volume Sampling

--> Quantum Physics arXiv:2608.13654 (quant-ph) [Submitted on 13 Aug 2026] Title:Entanglement Negativity in Noisy Quantum Volume Sampling Authors:Elijah Pelofske, Stephan Eidenbenz View a PDF of the paper titled Entanglement Negativity in Noisy Quantum Volume Sampling, by Elijah Pelofske and 1 other authors View PDF HTML (experimental) Abstract:The Quantum Volume protocol uses scrambling random circuits to benchmark NISQ computers. Quantum Volume is generally well-regarded as a benchmark for small, noisy, quantum computers because it requires the quantum computer to implement many non-local entangling gates within a square-shaped circuit, which incentivizes high qubit count, long qubit coherence times, and low error rates on all hardware gates. Quantum Volume circuits inherently produce high-entanglement states that are fragile to errors and decoherence. The Quantum Volume benchmark measures an observable called heavy-output-probability (HOP), where an HOP of $0.5$ corresponds to complete loss of coherence, and in the limit of system size an HOP $\approx 0.84$ for a fully coherent quantum processor. Here, we numerically study the tradeoff between depolarizing noise, entanglement as quantified by the bipartite negativity measure, and HOP in quantum volume circuits. Our results contextualize prior small scale quantum volume demonstrations on quantum computers and highlight that under depolarizing noise, due to finite system size effects heavy output probabilities can be greater than $0.5$ while the bipartite negativity entanglement has been destroyed. This implies, although improbable, that a NISQ computer could pass the Quantum Volume benchmark test threshold of $2/3$ while the underlying quantum computation has no global entanglement -- albeit only for small $n$. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.13654 [quant-ph]   (or arXiv:2608.13654v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.13654 Focus to learn more arXi

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Open system probes of renormalization group flowquantum-computing

Open system probes of renormalization group flow

--> Quantum Physics arXiv:2608.13664 (quant-ph) [Submitted on 13 Aug 2026] Title:Open system probes of renormalization group flow Authors:Andrew Keefe, Brenden Bowen, Saptarshi Biswas, Albion Lawrence, Nishant Agarwal, Archana Kamal View a PDF of the paper titled Open system probes of renormalization group flow, by Andrew Keefe and 5 other authors View PDF HTML (experimental) Abstract:Open system probes can provide an efficient means to characterize quantum many-body systems by employing them as engineered environments. The key idea is to map long-range spatial correlations of the environment onto dynamical correlations in the evolution of a simple quantum probe. Using the example of a qubit coupled to a transverse-field Ising model, we show how the non-Markovian rate or spectral flow can be used to identify stable and unstable fixed points, infer scaling dimensions of relevant fields, and deduce the renormalization group flow induced by deformations around any fixed point. Comments: Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics - Theory (hep-th) Cite as: arXiv:2608.13664 [quant-ph]   (or arXiv:2608.13664v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.13664 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Archana Kamal [view email] [v1] Thu, 13 Aug 2026 18:03:49 UTC (1,088 KB) Full-text links: Access Paper: View a PDF of the paper titled Open system probes of renormalization group flow, by Andrew Keefe and 5 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-08 Change to browse by: cond-mat cond-mat.mes-hall cond-mat.stat-mech hep-th References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation

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Efficient Hamiltonian Truncation: Fast Matrix Construction and Quantum Krylov Diagonalizationquantum-computing

Efficient Hamiltonian Truncation: Fast Matrix Construction and Quantum Krylov Diagonalization

--> Quantum Physics arXiv:2608.13691 (quant-ph) [Submitted on 13 Aug 2026] Title:Efficient Hamiltonian Truncation: Fast Matrix Construction and Quantum Krylov Diagonalization Authors:Rachel Houtz, Marco Knipfer, Konstantin Matchev, Alexander Roman, Mia West View a PDF of the paper titled Efficient Hamiltonian Truncation: Fast Matrix Construction and Quantum Krylov Diagonalization, by Rachel Houtz and 4 other authors View PDF HTML (experimental) Abstract:Hamiltonian truncation offers a nonperturbative route to quantum field theory, yet its accuracy is limited by the rapid expansion of the truncated Hilbert space, which drives up computational cost. We tackle this bottleneck with a hybrid strategy that pairs classical and quantum algorithms: 1) we develop an efficient basis-generation scheme built on integer partitions; 2) we speed up the construction of the sparse Hamiltonian matrix using symmetry-aware algorithms; and 3) we explore quantum Krylov diagonalization as a route to the low-lying spectrum. Benchmarking against the free massive scalar and $\phi^4$ theories in two spacetime dimensions, we achieve substantial gains in the computational efficiency of Hamiltonian truncation and chart a path toward future quantum implementations. Comments: Subjects: Quantum Physics (quant-ph); High Energy Physics - Lattice (hep-lat); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th) Report number: KA-TP-19-2026 Cite as: arXiv:2608.13691 [quant-ph]   (or arXiv:2608.13691v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.13691 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Mia West [view email] [v1] Thu, 13 Aug 2026 18:37:19 UTC (5,055 KB) Full-text links: Access Paper: View a PDF of the paper titled Efficient Hamiltonian Truncation: Fast Matrix Construction and Quantum Krylov Diagonalization, by Rachel Houtz and 4 other authorsView PDFHTML (experimental)TeX Sourc

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Scalable Test of Genuine Multipartite Entanglement via Partially Randomized Measurementsquantum-computing

Scalable Test of Genuine Multipartite Entanglement via Partially Randomized Measurements

--> Quantum Physics arXiv:2608.13725 (quant-ph) [Submitted on 13 Aug 2026] Title:Scalable Test of Genuine Multipartite Entanglement via Partially Randomized Measurements Authors:Jan Wojcik, Pawel Chrabkowski, Wieslaw Laskowski View a PDF of the paper titled Scalable Test of Genuine Multipartite Entanglement via Partially Randomized Measurements, by Jan Wojcik and 2 other authors View PDF HTML (experimental) Abstract:Certifying genuine multipartite entanglement in quantum systems can require a number of measurements that grows exponentially with the system size. Here we introduce a criterion based on correlation-tensor subsector lengths restricted to local measurement planes and show that it can be evaluated using partially randomized measurements without an explicit exponential dependence on the number of qubits. We derive the corresponding bounds for $k$-separable states and illustrate the criterion using representative families of multipartite entangled states. Finally, we demonstrate the practical applicability of the method on an ion-trap quantum computer by certifying genuine five-partite entanglement. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.13725 [quant-ph]   (or arXiv:2608.13725v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.13725 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Wieslaw Laskowski [view email] [v1] Thu, 13 Aug 2026 19:37:49 UTC (131 KB) Full-text links: Access Paper: View a PDF of the paper titled Scalable Test of Genuine Multipartite Entanglement via Partially Randomized Measurements, by Jan Wojcik and 2 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-08 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bo

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Designing robust molecular spins for quantum technologies with theoretical chemistryquantum-computing

Designing robust molecular spins for quantum technologies with theoretical chemistry

--> Quantum Physics arXiv:2608.13744 (quant-ph) [Submitted on 13 Aug 2026] Title:Designing robust molecular spins for quantum technologies with theoretical chemistry Authors:Timothy J. Krogmeier, Pranay Venkatesh, Mikayla Z. Fahrenbruch, Anthony W. Schlimgen, Andres Montoya-Castillo, Kade Head-Marsden View a PDF of the paper titled Designing robust molecular spins for quantum technologies with theoretical chemistry, by Timothy J. Krogmeier and 5 other authors View PDF HTML (experimental) Abstract:Molecular spins represent a versatile platform for quantum information science, with the potential to offer chemically tunable, addressable qubits. However, achieving this requires understanding and mitigating quantum decoherence. This Chapter provides a theoretical overview of current state-of-the-art chemical theory connecting ab initio electronic structure with open quantum system dynamics to guide the rational design of long-lived molecular qubits. Beginning at the electronic level, multi-reference and relativistic electronic structure methods to parameterize effective spin Hamiltonians are discussed, with a primary focus on accurately capturing $g$-tensors, zero-field splitting, and hyperfine interactions. These parameters feed into models of spin-phonon and spin-spin coupling to quantify $T_1$ and $T_2$ relaxation across various environmental regimes. This Chapter evaluates a hierarchy of dynamical methods, ranging from factorization to matrix product state approaches, balancing computational cost against accuracy and generalizability. Ultimately, mapping these theoretical models to molecular architecture can establish design principles, such as isotopic substitution and spatial spin delocalization, to understand and extend coherence lifetimes. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.13744 [quant-ph]   (or arXiv:2608.13744v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.13744 Focus to learn more arXiv-issued DOI via Data

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Fast classical simulation of `Fast, accurate, high-resolution simulation of large-scale Fermi-Hubbard models on a digital quantum processor'quantum-computing

Fast classical simulation of `Fast, accurate, high-resolution simulation of large-scale Fermi-Hubbard models on a digital quantum processor'

--> Quantum Physics arXiv:2608.13805 (quant-ph) [Submitted on 13 Aug 2026] Title:Fast classical simulation of `Fast, accurate, high-resolution simulation of large-scale Fermi-Hubbard models on a digital quantum processor' Authors:Xiao-Yu Ouyang, Runze Chi, Garnet Kin-Lic Chan View a PDF of the paper titled Fast classical simulation of `Fast, accurate, high-resolution simulation of large-scale Fermi-Hubbard models on a digital quantum processor', by Xiao-Yu Ouyang and 1 other authors View PDF HTML (experimental) Abstract:We study the Néel quench dynamics of a 1D Fermi-Hubbard model which has recently been simulated on quantum hardware. We demonstrate that the set of 7260 observable trajectories measured in the quantum experiment can be obtained more quickly and accurately through classical tensor network simulation using modest computation. Our result relies on transverse tensor network contraction, where a bond dimension of 32 is already sufficient to reproduce the quantum experiment. We further extend the converged observable trajectories to longer times than in the hardware simulation and in other recent classical simulations. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.13805 [quant-ph]   (or arXiv:2608.13805v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.13805 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Xiao-Yu Ouyang [view email] [v1] Thu, 13 Aug 2026 22:31:30 UTC (1,382 KB) Full-text links: Access Paper: View a PDF of the paper titled Fast classical simulation of `Fast, accurate, high-resolution simulation of large-scale Fermi-Hubbard models on a digital quantum processor', by Xiao-Yu Ouyang and 1 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-08 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loa

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Resource-efficient quantum eigenvalue transform with commutator scalingquantum-computing

Resource-efficient quantum eigenvalue transform with commutator scaling

--> Quantum Physics arXiv:2608.13862 (quant-ph) [Submitted on 14 Aug 2026] Title:Resource-efficient quantum eigenvalue transform with commutator scaling Authors:Arul Rhik Mazumder, James D. Watson, Samson Wang View a PDF of the paper titled Resource-efficient quantum eigenvalue transform with commutator scaling, by Arul Rhik Mazumder and 2 other authors View PDF Abstract:We develop quantum algorithms for estimating properties of general matrix functions of Hermitian matrices, with applications to phase estimation, Green's function evaluation, and estimating measurement distributions of time-evolved states. The resulting methods exhibit commutator scaling in matrix parameters similar to that usually found for product formulae, lower circuit depth in other parameters, and require only a single ancillary qubit. Our central primitive consists of classically postprocessing randomly chosen product formulae circuits, which mathematically corresponds to an approximation of a Richardson extrapolation. Within our framework, we introduce a protocol for approximating the measurement distributions of quantum states, extending beyond standard observable estimation. We also provide tightened gate complexity bounds for practically relevant systems, including those with k-local interactions, long-tailed matrix ensembles, and conserved quantities. Finally, numerical experiments confirm that our method can achieve significantly shallower circuit depths than standard product formulae in certain parameter regimes, and highlight the potential of their heuristic application. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.13862 [quant-ph]   (or arXiv:2608.13862v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.13862 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Samson Wang [view email] [v1] Fri, 14 Aug 2026 01:23:30 UTC (740 KB) Full-text links: Access Paper: View a PDF of the paper titled

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Robust Quantum Extremal Numbersquantum-computing

Robust Quantum Extremal Numbers

--> Quantum Physics arXiv:2608.13907 (quant-ph) [Submitted on 14 Aug 2026] Title:Robust Quantum Extremal Numbers Authors:Wanchen Zhang, Zicheng Han, Xiande Zhang View a PDF of the paper titled Robust Quantum Extremal Numbers, by Wanchen Zhang and 1 other authors View PDF HTML (experimental) Abstract:Absolutely maximally entangled states require every reduction of at most half of the parties to be maximally mixed, a condition that is both rigid and often impossible for qubit systems. Previous work introduced the quantum extremal number, which maximizes the number of exactly maximally mixed half-body marginals, and determined the exact value Qex(8,4)=56. The present work develops a robust extension of this extremal problem. For a subsystem $A$, the marginal maximal-mixing defect is defined by \[ D_A=2^{|A|}\operatorname{Tr}(\rho_A^2)-1 =2^{|A|}\left\|\rho_A-\frac{I_A}{2^{|A|}}\right\|_2^2, \] and $Q_{\mathrm{ex},\varepsilon}^{D}(n,k)$ is defined as the maximum number of $k$-body marginals satisfying $D_A\leq\varepsilon$ in an $n$-qubit pure state. This counting problem differs from approximate $k$-uniformity, which requires all $k$-body marginals to obey a common error bound. For pure states on $4m$ qubits, the following local stability inequality is established: \[ \sum_{i\in T}D_{T\setminus\{i\}}\geq1 \qquad (|T|=2m+1). \] It follows that, whenever $\varepsilon<1/(2m+1)$, the hypergraph of $\varepsilon$-good $2m$-subsets is $K_{2m+1}^{(2m)}$-free. Combined with the known exact eight-qubit construction, this yields the stability plateau \[ Q_{\mathrm{ex},\varepsilon}^{D}(8,4)=56, \qquad 0\leq\varepsilon<\frac15. \] For odd systems of $2k+1$ qubits, the exact forbidden hypergraph $H_k$ is used to derive explicit finite-error stability radii. In particular, $Q_{\mathrm{ex},\varepsilon}^{D}(9,4)\leq120$ for $0\leq\varepsilon<1/17$. These results turn exact quantum Turán obstructions into quantitative robustness statements and identify intervals on which quantum

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Circuit Depth Compression via Spectral Gap Amplification in Quantum Phase Estimationquantum-computing

Circuit Depth Compression via Spectral Gap Amplification in Quantum Phase Estimation

--> Quantum Physics arXiv:2608.14002 (quant-ph) [Submitted on 14 Aug 2026] Title:Circuit Depth Compression via Spectral Gap Amplification in Quantum Phase Estimation Authors:Sk Mujaffar Hossain, Satadeep Bhattacharjee View a PDF of the paper titled Circuit Depth Compression via Spectral Gap Amplification in Quantum Phase Estimation, by Sk Mujaffar Hossain and 1 other authors View PDF HTML (experimental) Abstract:We show that quantum phase estimation (QPE) circuits can be significantly compressed in depth by preprocessing the input operator with a sigmoid spectral filter before estimation. For systems with small spectral gaps Delta_lambda, standard QPE requires m = ceil(log2(1/Delta_lambda)) precision qubits and depth Theta(2^m). Applying a soft-step transformation f(lambda; tau,w) amplifies the effective gap to Delta_f > Delta_lambda (for w < 1/4), reducing the required precision to m_f = ceil(log2(1/Delta_f)) and compressing circuit depth by 2^(alpha Delta_m), where alpha = 1 for the LMR density-matrix exponentiation framework and alpha is in [0.11,0.42] for controlled-phase-gate circuits. We prove that this compression is exact, bounded above by log2(1/(4w Delta_lambda)) + 1, and impossible for exactly degenerate spectra. We further show that the threshold parameter tau requires only O(w) accuracy, so classical preprocessing such as covariance diagonalisation or CASSCF avoids circularity. A net resource advantage occurs when 4w^2(2^Delta_m - 1) > Delta_lambda log(1/epsilon). Validation on LiH and BeH2 bond-stretch calculations, classical covariance datasets, and synthetic near-degenerate cases demonstrates depth reductions of up to 27x and CX-gate reductions of up to 21x. For LiH, QPE output fidelity improves from 0.66 to 0.98 at a 1% hardware error rate. The method preserves the principal subspace to machine precision, requires no modification of QPE, and can be combined with readout-stage and state-preparation filtering. Negative-control tests establish

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The Company Lab Launches CO.LAB Q Commercialization Studio to Scale Quantum Startupsquantum-computing

The Company Lab Launches CO.LAB Q Commercialization Studio to Scale Quantum Startups

The Company Lab Launches CO.LAB Q Commercialization Studio to Scale Quantum Startups Chattanooga-based startup accelerator The Company Lab (CO.LAB) has launched CO.LAB Q, a 12-month quantum commercialization studio designed to translate early-stage quantum research into market-ready companies. Set to begin its inaugural cohort in November 2026, the program offers individualized commercialization pathways, pilot access, and technical infrastructure across quantum computing, networking, cybersecurity, sensing, and control hardware. [ CO.LAB Q Commercialization Studio Architecture ] │ ┌────────────────────────────────────────┼────────────────────────────────────────┐ ▼ ▼ ▼ Founding Technology & Utility Partners Academic & Defense Partners Quantum Infrastructure Access • Quantinuum (Founding Compute Partner). • UTC (Founding Academic Partner). • EPB Quantum Network. • Middle Tennessee Electric (Utility). • Davidson Technologies (Defense). • Oak Ridge National Laboratory (ORNL). • EPB Quantum (Network Partner). • Defense Pilot & SBIR/STTR Pathways. • UTC Quantum Center Facilities. The studio provides customized, milestone-driven support structured around foundational ecosystem partnerships: Quantum Computing & Cloud Access: As Founding Compute Partner, Quantinuum provides participating startups with direct access to its trapped-ion quantum processors, the Nexus cloud platform, the Guppy programming language, and technical simulation tools. Defense & National Security Track: Founding Defense Track Sponsor Davidson Technologies mentors startups on Department of Defense (DoD) mission needs, offering access to its quantum laboratory, cybersecurity frameworks, and pilot pathways through DIU and SBIR/STTR programs. Academic & Facility Integration: Founding Academic Partner University of Tennessee at Chattanooga (UTC) connects startups with quantum faculty, student researchers, and specialized laboratory facilities. Grid & Utility Testing: Founding U

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Brazilian Researchers Demonstrate Universal Single-Qubit Gates with One Pulsequantum-computing

Brazilian Researchers Demonstrate Universal Single-Qubit Gates with One Pulse

Researchers at Universidade Federal de São Carlos (UFSCar) have demonstrated a new method for constructing any single-qubit quantum gate using a simplification: a single electromagnetic pulse. Building high fidelity quantum gates is a fundamental task for quantum computing. In the case of single-qubit gates, constructing arbitrary gates with a sequence of pulses is in principle straightforward, as demonstrated by Kok et al. and Häffner et al. The team obtained this result by inverting the equation of motion for the evolution operator, a standard method for obtaining the formula. This approach relies only on the rotating-wave-approximation, the only approximation involved, potentially streamlining implementation. Single-Qubit Gate Generation with Linearly-Polarized Fields A single, carefully shaped pulse of light can now enact any single-qubit quantum gate, a feat previously requiring complex sequences of multiple pulses. This advancement does not offer a pathway to simplify hardware and boost operational fidelity. This isn’t merely finding a solution; it’s a determination of the gate creation process, offering a level of analytical control previously elusive. Unlike many existing methods that rely on numerical optimization, this technique yields closed, analytical formulas for the control pulses, making them more readily implementable in physical systems. The control field itself is generated using a relatively simple electromagnetic waveform. The researchers specify that any desired one-qubit gate corresponding to a special unitary matrix can be generated by this single, shaped pulse. This contrasts with earlier methods, such as those detailed by Kok et al. (2007); Häffner et al. (2008); Saffman (2016); Lucero et al. (2008), who used pulse sequences to achieve similar results. The process involves defining two functions, a(t) and b(t), which dictate the pulse’s amplitude and phase, and then solving an integral equation to determine the precise waveform. The paper e

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Quantinuum and Quanta Computer Partner to Industrialize Fault-Tolerant Trapped-Ion Hardware Manufacturingquantum-computing

Quantinuum and Quanta Computer Partner to Industrialize Fault-Tolerant Trapped-Ion Hardware Manufacturing

Quanta Computer and Quantinuum Partner to Industrialize Fault-Tolerant Trapped-Ion Hardware Manufacturing Trapped-ion quantum computing developer Quantinuum (NASDAQ: QNT) and Fortune Global 500 electronics manufacturer Quanta Computer have signed a collaborative development agreement to industrialize the hardware infrastructure, systems engineering, and mass-manufacturing supply chains for future generations of Quantinuum’s quantum computers. The partnership bridges Quantinuum’s trapped-ion Quantum Charge-Coupled Device (QCCD) architecture with Quanta’s global electronics manufacturing and cloud-server infrastructure expertise. Joint engineering teams are actively designing modular, manufacturable hardware subsystems intended to transition quantum hardware from custom-built, laboratory-assembled systems to standardized, mass-producible enterprise IT hardware. [ Quantinuum & Quanta Hardware Industrialization Pipeline ] │ ┌────────────────────────────────────────┴────────────────────────────────────────┐ ▼ ▼ Quantinuum Trapped-Ion Architecture Quanta Global Industrial Infrastructure • QCCD Junction & Barium-Ion Control Roadmaps. • Scalable High-Precision Hardware Assembly. • Sub-System Miniaturization & Modularization. • Enterprise Cloud-Rack Form Factor Standardization. • Commercial Fault-Tolerant QPU Milestones. • Global Electronics Supply Chain Integration. The collaboration focuses on scaling physical hardware assembly to support Quantinuum’s roadmap toward fault-tolerant, megaquop-class systems: Hardware Modularization: Co-engineering standardized, rack-mountable enclosures, environmental packaging, and high-density interface interconnects for trapped-ion systems. Supply Chain Stabilization: Establishing robust, high-volume component procurement pipelines for sub-system electronics, laser/optical assemblies, and RF control hardware. Scalable Production Systems: Transitioning from low-volume custom assembly to automated manufacturing lines capable of d

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Tried implementing the NAND-tree algorithm in Qiskitquantum-computing

Tried implementing the NAND-tree algorithm in Qiskit

I've been working on a Qiskit implementation of the NAND-tree quantum algorithm and thought I'd share it here. Right now it works with small finite trees. I implemented the quantum walk, the input oracle, query counting, and a few different ways of simulating the Hamiltonian. I've mostly been testing it on 2, 4, and 8 leaves. It's not a scalable implementation yet. Some parts still use dense Hamiltonian matrices, and figuring out how to get past that is one of the things I'm looking into. Here's the repo: https://github.com/mncrftfrcnm/qiskit-nand-tree-implementation If anyone here has worked with NAND-tree algorithms or quantum walks, I'd really appreciate feedback, especially if you spot something wrong with how I've handled the oracle or query counting. submitted by /u/FollowingEvery4802 [link] [comments]

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Quantinuum to Partner with the Singapore Institute of Technology to Help Develop Singapore’s Future Quantum Workforce.quantum-computing

Quantinuum to Partner with the Singapore Institute of Technology to Help Develop Singapore’s Future Quantum Workforce.

Quantinuum to Partner with the Singapore Institute of Technology to Help Develop Singapore’s Future Quantum Workforce. Quantinuum has signed a Memorandum of Understanding (MoU) with the Singapore Institute of Technology (SIT) to train and expand Singapore’s quantum workforce. Building on Quantinuum’s existing R&D footprint and the planned deployment of its Helios quantum processor in Singapore, the collaboration aims to prepare an industry-ready workforce across engineering, systems development, and applied technologies. Key Initiatives of the Partnership Practical Curriculum: Joint development of hands-on training modules tailored for both undergraduate students and working professionals. Tool Access: Direct access to Quantinuum’s suite of quantum software, development tools, and simulators for educational use. Community Engagement: Hosting regular workshops, seminars, and campus events to build local interest and technical literacy in quantum computing. This strategic alignment addresses the growing commercial demand for skilled talent, ensuring local developers and engineers gain direct exposure to state-of-the-art quantum hardware and software environments. Additional information can be found in a LinkedIn post here. August 15, 2026 dougfinke2026-08-15T20:43:39-07:00 Leave A Comment Cancel replyComment Type in the text displayed above Δ This site uses Akismet to reduce spam. Learn how your comment data is processed.

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Lattice-Based Cryptography Explainedquantum-computing

Lattice-Based Cryptography Explained

Lattice-based cryptography is the branch of modern encryption that hides its secrets inside a grid of points in high-dimensional space. It is the mathematics underneath the two headline standards the United States published in 2024, and it is the reason most of the internet’s future key exchanges will look nothing like the ones running today. This page is about the machinery rather than the policy. If you want the wider picture of the migration, our guide to post-quantum cryptography covers it, and the vendor landscape is mapped separately. What follows is the geometry that lattice-based cryptography is built from, the hard problems, the protocols standing on them, and an honest account of why anyone believes a quantum computer cannot break them. Core assumption Finding short or close vectors in a high-dimensional lattice is hard, even with a quantum computer Workhorse problem Learning With Errors, introduced by Oded Regev in 2005 Standardised as ML-KEM in FIPS 203 and ML-DSA in FIPS 204, both published 13 August 2024 Descended from CRYSTALS-Kyber and CRYSTALS-Dilithium, submitted to the NIST process in November 2017 Status of the security claim No known efficient quantum attack, which is not the same thing as a proof Practical cost Keys and signatures measured in kilobytes rather than tens of bytes Key takeaways A lattice is a repeating grid of points, and the hard part is finding the nearest one. In two dimensions a child can do it by eye, and in the several hundred dimensions lattice-based cryptography uses, nobody knows how. The same lattice can be described by an easy basis or an impossible one. That asymmetry between a short near-orthogonal description and a long skewed one is the trapdoor the whole field is built on. Learning With Errors is linear algebra with the answers slightly wrong. Remove the errors and the system falls to schoolbook elimination, add them back and no efficient method is known. Quantum resistance here is an absence of attack, not a theor

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Quantum Zeitgeist Weekly Digestquantum-computing

Quantum Zeitgeist Weekly Digest

Welcome to this week’s quantum technology digest. The articles below cover advances across the quantum computing stack, from hardware development and error correction to algorithmic improvements and commercial growth. Several companies reported significant progress this week, indicating continued momentum in the field. This week’s updates demonstrate a clear focus on scaling and refinement. Quantinuum features prominently with announcements regarding both hardware manufacturing partnerships and algorithmic efficiency gains. Other companies, including IonQ and Pasqal, are pushing boundaries in error correction and qubit control. Funding news from D-Wave and Infleqtion’s strong revenue growth further illustrate increasing investment and market demand. Overall, this week highlights practical steps toward building more capable and accessible quantum systems. Progress isn’t limited to a single approach; diverse modalities – superconducting, trapped ion, and neutral atom – all saw encouraging developments. The increasing availability of quantum resources on cloud platforms like Oracle also suggests a move toward wider accessibility for researchers and developers. 1. Quanta Computer & Quantinuum Partner to Scale Quantum Computing Hardware Quantinuum and Quanta Computer are collaborating to manufacture infrastructure for large-scale quantum computers. The partnership combines Quantinuum’s quantum technology with Quanta’s manufacturing expertise, shifting focus from research toward deployable systems. This co-development effort aims to improve the modularity and scalability of quantum processors, supporting Quantinuum’s roadmap for fault-tolerant quantum systems. Quanta’s experience in industrializing advanced computing will establish supply chains and manufacturing processes needed for wider quantum access. Read more 2. IBM’s QOBLIB Library Demonstrates Quantum Advantage in Optimization IBM and its partners announced demonstrations of quantum advantage in optimization t

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