Security of Binary-Modulated Optical Key Distribution Against Quantum-Enhanced Coherent Eavesdropping

Quantum Physics [Submitted on 20 Mar 2026] Security of Binary-Modulated Optical Key Distribution Against Quantum-Enhanced Coherent Eavesdropping Karol Łukanowski, Michał Wójcik, Stefano Olivares, Konrad Banaszek, Marcin Jarzyna Optical key distribution (OKD) protects the physical layer of communication links by taking advantage of the inherent noise present in the photodetection process. It allows for efficient generation of a shared random key between two distant users which can subsequently be used for cryptographic purposes secure against passive eavesdropping. Moreover, it can be straightforwardly implemented over standard intensity modulation and direct detection links, making it an attractive alternative to quantum key distribution. Here we present a comprehensive security analysis against more powerful eavesdroppers possessing either the ability to perform coherent detection, or even quantum-optimal measurements on the intercepted transmission. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2603.20395 [quant-ph]   (or arXiv:2603.20395v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2603.20395 Focus to learn more Submission history From: Karol Łukanowski [view email] [v1] Fri, 20 Mar 2026 18:15:22 UTC (206 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-03 References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation 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 Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)