Improved composable key rates for CV-QKD

TL;DR

This paper refines the theoretical framework for calculating composable key rates in continuous-variable quantum key distribution, leading to more accurate and optimistic security assessments.

Contribution

It provides a more rigorous formulation for the composable key rate of generic CV-QKD protocols, improving upon previous theoretical models.

Findings

More optimistic key rate formulas derived

Enhanced theoretical understanding of finite-size effects

Improved security proof rigor 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.