Go-and-return phase encoded SR QKD and its security consideration

TL;DR

This paper analyzes the security of a phase-encoded coherent-state QKD scheme with a strong reference pulse, proposing a practical implementation and examining its security against soft filtering attacks.

Contribution

It introduces a two-pass phase encoding scheme with a strong reference pulse and provides security analysis considering realistic equipment parameters.

Findings

Secure key rate relates to pulse energy and distance.

The proposed scheme is experimentally stable.

Solutions address shadowing by bright reference pulses.

Abstract

In this work, we study the security of coherent-state quantum key distribution with a strong reference pulse. The consideration is based on a powerful soft filtering attack and uses realistic parameters of the equipment. Our model allows us to relate the secure key generation rate and distance with the energy of signal and reference pulses. We propose a two-pass quantum key distribution phase encoding optical scheme with a strong reference pulse. This simple for realization scheme is experimentally tested showing stable operation. Here we describe the tuning technique and solution for the problem of weak signal pulse shadowing by a bright reference pulse with the relative intensity difference of more than 60\,dB between them.