Effective discrete-modulated continuous variable QKD under general attacks using dimension reduction

Abstract:Continuous variable quantum key distribution via discrete modulations ensures information-theoretic security using standard telecom technologies, providing affordable and scalable quantum communications with simplified classical postprocessing. However, existing security proofs against general attacks often rely on restrictive assumptions, such as a bounded dimension for coherent states, or require impractically large block sizes. In this work, we develop a finite-size security analysis that removes these limitations while incorporating realistic experimental features. Our approach combines an optimization under infinite dimensions, a security proof against general attacks, a trusted detector model accounting for the receiver imperfections, and postselection strategies to reuse discarded measurement outcomes. We report positive key rates in the finite-size regime for relevant block sizes of the order of $10^7$. These results contribute to narrowing the gap between theoretical security proofs and practical implementations of discrete-modulated continuous variable quantum key distribution protocols.

32 pages, 4 figs. V2: added hyperplane approximation, correction on dimension reduction term and general improvements

arXiv:2606.20346 [quant-ph]

(or arXiv:2606.20346v2 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2606.20346 Focus to learn more arXiv-issued DOI via DataCite

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