Fundamental Limits on QBER and Distance in Quantum Key Distribution
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Quantum Physics arXiv:2602.22319 (quant-ph) [Submitted on 25 Feb 2026] Title:Fundamental Limits on QBER and Distance in Quantum Key Distribution Authors:Stefano Pirandola View a PDF of the paper titled Fundamental Limits on QBER and Distance in Quantum Key Distribution, by Stefano Pirandola View PDF HTML (experimental) Abstract:Quantum key distribution (QKD) enables information-theoretic secure communication, yet its ultimate tolerance to noise and achievable transmission distance remain fundamentally constrained. We establish the maximum quantum bit error rate (QBER) compatible with secure QKD and derive corresponding upper bounds on communication distance. Our results follow from a fundamental capacity threshold for qubit Pauli channels and apply to protocols based on two or more mutually unbiased bases, using either single-photon or weak coherent sources. By connecting information-theoretic limits to realistic physical noise models, we obtain universal bounds on achievable distances in fiber and free-space links, including diffraction-limited constraints relevant to deep-space quantum communications. These findings clarify the ultimate noise robustness of QKD and delineate the fundamental boundaries of secure quantum communication. Comments: Subjects: Quantum Physics (quant-ph); Mathematical Physics (math-ph); Applied Physics (physics.app-ph); Optics (physics.optics); Space Physics (physics.space-ph) Cite as: arXiv:2602.22319 [quant-ph] (or arXiv:2602.22319v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.22319 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Stefano Pirandola [view email] [v1] Wed, 25 Feb 2026 19:00:02 UTC (41 KB) Full-text links: Access Paper: View a PDF of the paper titled Fundamental Limits on QBER and Distance in Quantum Key Distribution, by Stefano PirandolaView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-02 Change to browse by: math math-ph math.MP physics physics.app-ph physics.optics physics.space-ph 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?)