Quantum secure direct communication with heralded superposition source of squeezed states

Quantum secure direct communication with heralded superposition source of squeezed states | 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 Research Article Quantum secure direct communication with heralded superposition source of squeezed states Jin-Yu Wang, Jia-Wei Ying, Qi Zhang, Shi-Pu Gu, Xing-Fu Wang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6737068/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Apr, 2026 Read the published version in Quantum Information Processing → Version 1 posted 7 You are reading this latest preprint version Abstract Quantum secure direct communication (QSDC) promises unconditional security for direct information transmission without pre-shared keys. However, practical implementations using weak coherent sources face critical challenges from device imperfections, such as emitting vacuum states and multiphoton states. Here, we introduce a heralded QSDC protocol leveraging squeezed-state superposition in a cross-Kerr nonlinear medium, where single-mode squeezed states interfere with coherent states to generate superposition states via post-measurement selection. We have considered three detector models to analyze the heralding performance of light sources under different conditions, including the ideal photon number detector, the practical photon number detector, and the practical photon detector. Our proposed protocol dramatically reduces the vacuum state ratio compared to weak coherent pulse sources, and the multiphoton ratio is still maintained at a low level, significantly enhancing the security information capacity and the maximum secure communication distance. We perform numerical simulations and compare our protocol with the optical single-photon-based QSDC protocol. At 7.5 km with an average photon number of 0.01, the security information capacity improves by 13.42 times, 12.20 times, and 8.64 times for three detector models. Extending to 17.5 km, these gains will be to 277.59 times, 251.58 times, and 172.91 times. Our work provides a robust framework for high-capacity, long-distance, secure quantum communication systems. PACS numbers: 03.67.Pp, 03.67.Hk, 03.65.Ud superposition of squeezed states cross-Kerr nonlinear medium heralded QSDC protocol photon number detector Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 18 Apr, 2026 Read the published version in Quantum Information Processing → Version 1 posted Editorial decision: Revision requested 13 Oct, 2025 Reviews received at journal 11 Sep, 2025 Reviewers agreed at journal 20 Aug, 2025 Reviewers invited by journal 19 Aug, 2025 Editor assigned by journal 28 May, 2025 Submission checks completed at journal 27 May, 2025 First submitted to journal 24 May, 2025 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. 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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-6737068","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":504860525,"identity":"78977f7b-8c83-4f73-bb2a-49c6919fec79","order_by":0,"name":"Jin-Yu Wang","email":"","orcid":"","institution":"Nanjing University of Posts and Telecommunications","correspondingAuthor":false,"prefix":"","firstName":"Jin-Yu","middleName":"","lastName":"Wang","suffix":""},{"id":504860526,"identity":"2337396c-ab42-47de-8ae9-e600d1d55450","order_by":1,"name":"Jia-Wei Ying","email":"","orcid":"","institution":"Nanjing University of Posts and 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However, practical implementations using weak coherent sources face critical challenges from device imperfections, such as emitting vacuum states and multiphoton states. Here, we introduce a heralded QSDC protocol leveraging squeezed-state superposition in a cross-Kerr nonlinear medium, where single-mode squeezed states interfere with coherent states to generate superposition states via post-measurement selection. We have considered three detector models to analyze the heralding performance of light sources under different conditions, including the ideal photon number detector, the practical photon number detector, and the practical photon detector. Our proposed protocol dramatically reduces the vacuum state ratio compared to weak coherent pulse sources, and the multiphoton ratio is still maintained at a low level, significantly enhancing the security information capacity and the maximum secure communication distance. 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