Fast charge noise sensing using a spectator valley state in asinglet-triplet qubit

Fast charge noise sensing using a spectator valley state in asinglet-triplet qubit | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Fast charge noise sensing using a spectator valley state in asinglet-triplet qubit David W. Kanaar, Yasuo Oda, Mark F. Gyure, J. P. Kestner This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8857776/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Semiconductor spin qubits are a promising platform for quantum computing but remain vulnerable tocharge noise. Accurate, in situ measurement of charge noise could enable closed-loop control andimprove qubit performance. Here, we propose a method for real-time detection of charge noise usinga silicon singlet-triplet qubit in which one electron is initialized in an excited valley state. This valleyexcitation acts as a spectator degree of freedom coupled to a high-quality resonator via the exchangeinteraction, which is sensitive to charge-noise-induced voltage fluctuations. Dispersive readout of theresonator enables a continuous, classical measurement of exchange fluctuations during qubitoperation. Signal-to-noise analysis shows that, under realistic device parameters, sub-millisecondmeasurement times are achievable using a quantum-limited amplifier. Even without such an amplifier,similar performance is achievable with appropriately engineered resonator parameters. This approachenables real-time monitoring of slow drifts in exchange, opening the door to feedback and feedforwardstrategies for maintaining high-fidelity quantum operations. Importantly, the protocol preserves spincoherence and can be executed concurrently with qubit logic gates. Physical sciences/Engineering Physical sciences/Physics Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers invited by journal 16 Mar, 2026 Editor assigned by journal 17 Feb, 2026 Submission checks completed at journal 17 Feb, 2026 First submitted to journal 12 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8857776","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":606796089,"identity":"5d537f38-05d6-436e-92e7-a465e2fa5e5f","order_by":0,"name":"David W. 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Accurate, in situ measurement of charge noise could enable closed-loop control andimprove qubit performance. Here, we propose a method for real-time detection of charge noise usinga silicon singlet-triplet qubit in which one electron is initialized in an excited valley state. This valleyexcitation acts as a spectator degree of freedom coupled to a high-quality resonator via the exchangeinteraction, which is sensitive to charge-noise-induced voltage fluctuations. Dispersive readout of theresonator enables a continuous, classical measurement of exchange fluctuations during qubitoperation. Signal-to-noise analysis shows that, under realistic device parameters, sub-millisecondmeasurement times are achievable using a quantum-limited amplifier. Even without such an amplifier,similar performance is achievable with appropriately engineered resonator parameters. 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