Refined finite-size analysis of binary-modulation continuous-variable quantum key distribution

TL;DR

This paper improves the finite-size security analysis of binary-modulation continuous-variable quantum key distribution, achieving better key-rate scaling with transmission distance and potentially enabling comprehensive security proofs for similar protocols.

Contribution

It extends the security proof based on complementarity to finite-size regimes, significantly enhancing key-rate performance in binary-modulation CV-QKD protocols.

Findings

Key rate scales linearly with attenuation in the asymptotic limit

Significant improvements in finite-size key rates over previous analyses

Potential applicability to other discrete-modulation CV-QKD protocols

Abstract

Recent studies showed the finite-size security of binary-modulation CV-QKD protocols against general attacks. However, they gave poor key-rate scaling against transmission distance. Here, we extend the security proof based on complementarity, which is used in the discrete-variable QKD, to the previously developed binary-modulation CV-QKD protocols with the reverse reconciliation under the finite-size regime and obtain large improvements in the key rates. Notably, the key rate in the asymptotic limit scales linearly against the attenuation rate, which is known to be optimal scaling but is not achieved in previous finite-size analyses. This refined security approach may offer full-fledged security proofs for other discrete-modulation CV-QKD protocols.