Finite-size analysis of continuous-variable measurement-device-independent quantum key distribution

TL;DR

This paper analyzes how finite-size effects influence the performance and security of continuous-variable measurement-device-independent quantum key distribution, emphasizing parameter estimation, optimal modulation, and practical detection impacts.

Contribution

It provides a detailed finite-size analysis of CV-MDI QKD, including parameter estimation methods and the relationship between signal number and modulation variance, highlighting practical considerations.

Findings

Finite-size effects significantly reduce the secret key rate.

Proximity of Charlie to Bob maximizes transmission distance.

Finite-size effects must be considered for practical CV-MDI QKD implementations.

Abstract

We study the impact of the finite-size effect on the continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocol, mainly considering the finite-size effect on the parameter estimation procedure. The central-limit theorem and maximum likelihood estimation theorem are used to estimate the parameters. We also analyze the relationship between the number of exchanged signals and the optimal modulation variance in the protocol. It is proved that when Charlie's position is close to Bob, the CV-MDI QKD protocol has the farthest transmission distance in the finite-size scenario. Finally, we discuss the impact of finite-size effects related to the practical detection in the CV-MDI QKD protocol. The overall results indicate that the finite-size effect has a great influence on the secret key rate of the CV-MDI QKD protocol and should not be ignored.