Continuous-variable Quantum Key Distribution protocols with a discrete modulation

TL;DR

This paper analyzes the security of continuous-variable quantum key distribution protocols with discrete modulation, establishing their robustness against various attacks and providing lower bounds for secret key rates.

Contribution

It introduces security proofs for CV-QKD protocols with discrete modulation against collective attacks, including Gaussian and non-Gaussian noise, and derives key rate bounds.

Findings

Protocols are secure against collective Gaussian and linear attacks.

Lower bounds for secret key rates are established.

Security proofs leverage extremality properties of Gaussian states.

Abstract

In this paper, we consider continuous-variable quantum key distribution with a discrete modulation, either binary or quaternary. We establish the security of these protocols against the class of collective attacks that induce a linear quantum channel. In particular, all Gaussian attacks are taken into account, as well as linear attacks which add a non-Gaussian noise. We give lower bounds for the secret key rate using extremality properties of Gaussian states.