Finite-size analysis of continuous-variable quantum key distribution

TL;DR

This paper extends finite-size analysis to continuous-variable quantum key distribution, estimating secret key rates considering finite effects, and demonstrates the feasibility of secure keys over long distances.

Contribution

It adapts finite-size analysis methods to continuous-variable protocols, focusing on parameter estimation and revealing practical secure key generation over 50 km.

Findings

Finite-size effects significantly reduce key rates compared to asymptotic results.

Recent protocols can generate secure keys over distances greater than 50 km.

The analysis provides a more pessimistic but realistic estimate of secret key rates.

Abstract

The goal of this paper is to extend the framework of finite size analysis recently developed for quantum key distribution to continuous-variable protocols. We do not solve this problem completely here, and we mainly consider the finite size effects on the parameter estimation procedure. Despite the fact that some questions are left open, we are able to give an estimation of the secret key rate for protocols which do not contain a postselection procedure. As expected, these results are significantly more pessimistic than the ones obtained in the asymptotic regime. However, we show that recent continuous-variable protocols are able to provide fully secure secret keys in the finite size scenario, over distances larger than 50 km.