Alternative Anti-Quantum-Channel Disturbance Decoder for Quantum Key Distribution

TL;DR

This paper introduces a novel QKD decoder based on a Q-M interferometer that effectively counters polarization disturbances, enhancing stability and security over optical fibers.

Contribution

The paper presents a new anti-disturbance decoder for QKD using a Q-M interferometer, demonstrating immunity to polarization-induced fading and experimental stability over long fiber distances.

Findings

Stable QKD operation over 50.4 km fiber

Low quantum bit error rate achieved

Average secure key rate of 7.34 kbps

Abstract

In the letter, we propose an anti-quantum-channel disturbance decoder for quantum key distribution (QKD). The decoder is based on a quarter-wave plate reflector-Michelson (Q-M) interferometer, with which the QKD system can be free of polarization disturbance caused by quantum channel and optical devices in the system. The theoretical analysis indicates that the Q-M interferometer is immune to polarization-induced signal fading and its corresponding operator is Pauli Matrix {\sigma}2, which naturally satisfies the anti-disturbance condition. A Q-M interferometer based time-bin phase encoding QKD setup is demonstrated and the experimental results show that the QKD setup works stably with a low quantum bit error rate and an average safe key rate about 7.34 kbps over 50.4 km standard optical fiber for two hours in the lab.