Security against collective attacks for a continuous-variable quantum key distribution protocol using homodyne detection and postselection

TL;DR

This paper evaluates the security of a continuous-variable quantum key distribution protocol with homodyne detection and postselection against collective attacks, providing a lower bound on the secret key rate.

Contribution

It derives a lower bound on the secret key rate for the protocol and optimizes it for symmetric Gaussian channels, advancing security analysis methods.

Findings

Lower bound on secret key rate established

Optimized key rate for symmetric Gaussian channels

Enhanced understanding of security against collective attacks

Abstract

We analyze the security against collective attacks for a homodyne-based continuous-variable quantum key distribution protocol using binary coherent states and postselection. We derive a lower bound of the secret key rate in an asymptotic scenario, and numerically optimize it for the case of a symmetric Gaussian channel.