Improved composable key rates for CV-QKD

Abstract

Modern security proofs of quantum key distribution (QKD) must take finite-size effects and composable aspects into consideration. This is also the case for continuous-variable (CV) protocols which are based on the transmission and detection of bosonic coherent states. In this paper, we refine and advance the previous theory in this area providing a more rigorous formulation for the composable key rate of a generic CV-QKD protocol. Thanks to these theoretical refinements, our general formulas allow us to prove more optimistic key rates with respect to previous literature.

Discussion added to explain practical QKD implementation in a session of multiple blocks (new Section IV and Figure 3). Minor typos corrected. Improves theory from arXiv:2203.00706, arXiv:2010.04168, and arXiv:1912.11418