An improved two-way continuous-variable quantum key distribution protocol with added noise in homodyne detection

TL;DR

This paper introduces an improved two-way continuous-variable quantum key distribution protocol that incorporates added noise in homodyne detection, enhancing secret key rate and noise tolerance over fiber distances.

Contribution

It presents a novel two-way CV QKD protocol with added detection noise, demonstrating improved performance and security against collective attacks compared to existing methods.

Findings

Added noise increases secret key rate and noise tolerance.

Protocol achieves secure key distribution over 60 km fiber.

Performance remains superior to one-way protocols despite channel correlations.

Abstract

We propose an improved two-way continuous-variable quantum key distribution (CV QKD) protocol by adding proper random noise on the receiver's homodyne detection, the security of which is analysed against general collective attacks. The simulation result under the collective entangling cloner attack indicates that despite the correlation between two-way channels decreasing the secret key rate relative to the uncorrelated channels slightly, the performance of the two-way protocol is still far beyond that of the one-way protocols. Importantly, the added noise in detection is beneficial for the secret key rate and the tolerable excess noise of this two-way protocol. With the reasonable reconciliation efficiency of 90%, the two-way CV QKD with added noise allows the distribution of secret keys over 60 km fibre distance.