Quantum error correction of a grid-state qubit with state preparation and measurement errors below $10^{-3}$
This breakthrough reduces a critical bottleneck in grid-state qubits, enabling more reliable fault-tolerant quantum computation and narrowing the gap to practical large-scale systems.
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Quantum Physics arXiv:2607.06718 (quant-ph) [Submitted on 7 Jul 2026] Title:Quantum error correction of a grid-state qubit with state preparation and measurement errors below $10^{-3}$ Authors:Sara Turcotte (1,2), Lucas St-Jean (1), Amélie L. Pessonneaux (1), Ross Shillito (1), Bohdan Kulchytskyy (1), Eliott Ouellet (1), Jean Olivier Simoneau (1), Florian Hopfmueller (1), Matthew Hamer (1), Pascal Lemieux (1), Dany Lachance-Quirion (1), Baptiste Royer (2), Nicholas E. Frattini (1) ((1) Nord Quantique, (2) Département de Physique et Institut quantique, Université de Sherbrooke) View a PDF of the paper titled Quantum error correction of a grid-state qubit with state preparation and measurement errors below $10^{-3}$, by Sara Turcotte (1 and 15 other authors View PDF HTML (experimental) Abstract:Grid state qubits offer a hardware-efficient approach to large-scale fault-tolerant quantum computing. They access the information redundancy required for quantum error correction by exploiting the large Hilbert space naturally available in harmonic oscillators. Superconducting architectures are particularly suitable to implement grid state qubits due to their fast and high-fidelity operations. Grid states in superconducting circuits enable quantum error correction (QEC) with performance beyond break-even. However, the state preparation and measurements (SPAM) errors of grid states has been a significant limitation to computational performances. In this work, we leverage high-performance QEC to enable repeat-until-success state preparation of both cardinal and magic states of the single-mode grid-state qubit. We combine this with an improved measurement protocol that corrects for both finite-energy envelope and auxiliary qubit readout errors, and increases robustness to photon loss. Our experiments, using both techniques, achieve a combined state-preparation and measurement error below $10^{-3}$. This represents two orders-of-magnitude improvement over the state of the art, bringing this platform on par with standard SPAM error levels measured in transmon qubits. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2607.06718 [quant-ph] (or arXiv:2607.06718v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2607.06718 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Sara Turcotte [view email] [v1] Tue, 7 Jul 2026 18:34:42 UTC (9,992 KB) Full-text links: Access Paper: View a PDF of the paper titled Quantum error correction of a grid-state qubit with state preparation and measurement errors below $10^{-3}$, by Sara Turcotte (1 and 15 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-07 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv (What is alphaXiv?) Links to Code Toggle CatalyzeX Code Finder for Papers (What is CatalyzeX?) DagsHub Toggle DagsHub (What is DagsHub?) GotitPub Toggle Gotit.pub (What is GotitPub?) Huggingface Toggle Hugging Face (What is Huggingface?) ScienceCast Toggle ScienceCast (What is ScienceCast?) Demos Demos Replicate Toggle Replicate (What is Replicate?) Spaces Toggle Hugging Face Spaces (What is Spaces?) Spaces Toggle TXYZ.AI (What is TXYZ.AI?) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower (What are Influence Flowers?) Core recommender toggle CORE Recommender (What is CORE?) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs. Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)