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Stoquastic permutationally invariant Bell operators

arXiv Quantum Physics
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⚡ Quantum Brief
Researchers established the first link between permutationally invariant (PI) Bell operators and stoquastic Hamiltonians, revealing shared nonpositive off-diagonal matrix elements in key quantum experiments. The team introduced a "stoquasticity cone" framework to fully characterize stoquastic parameter regimes for any PI Bell operator, enabling precise mathematical classification. They proved that binary-input, binary-output PI Bell operators with up to three-body correlators can always be made stoquastic regardless of measurement parameters. Numerical analysis suggests the Bell operator used in recent large-scale experiments is already optimal for stoquasticity, validating current experimental approaches. The work demonstrates how stoquasticity can optimize quantum-classical gaps, offering potential improvements for quantum advantage in Bell correlation tests.
Stoquastic permutationally invariant Bell operators

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Quantum Physics arXiv:2603.22493 (quant-ph) [Submitted on 23 Mar 2026] Title:Stoquastic permutationally invariant Bell operators Authors:Jan Li, Owidiusz Makuta, Evert van Nieuwenburg, Jordi Tura View a PDF of the paper titled Stoquastic permutationally invariant Bell operators, by Jan Li and 3 other authors View PDF HTML (experimental) Abstract:As Hermitian operators, many-body Bell operators can naturally be identified as many-body Hamiltonians. An important subclass of such Hamiltonians is the stoquastic class, characterized by having nonpositive off-diagonal matrix elements in a given basis. Interestingly, this property is shared by the permutationally invariant (PI) Bell operators underlying the largest Bell-correlation experiments to date. In this work, we explore the connection between many-body PI Bell operators and stoquasticity. We introduce the stoquasticity cone, which allows for a full characterization of the stoquastic parameter regimes for any PI Bell operator. We use this to show that PI Bell operators of the binary-input binary-output scenario consisting of at most three-body correlators can always be rendered stoquastic for any set of measurement parameters. Additionally, we also provide examples that use the stoquasticity cone to optimize for the quantum-classical gap. Numerical evidence suggests that the Bell operator used in the largest experiments to date is optimal with respect to stoquasticity. To the best of our knowledge, this work establishes the first connection between PI Bell operators and stoquasticity. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2603.22493 [quant-ph] (or arXiv:2603.22493v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2603.22493 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Jan Li [view email] [v1] Mon, 23 Mar 2026 19:00:12 UTC (473 KB) Full-text links: Access Paper: View a PDF of the paper titled Stoquastic permutationally invariant Bell operators, by Jan Li and 3 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-03 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?) Links to Code Toggle Papers with Code (What is Papers with Code?) 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?)

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Source: arXiv Quantum Physics