Intrinsic-Stabilization Uni-Directional Quantum Key Distribution Between Beijing and Tianjin

TL;DR

This paper introduces a uni-directional quantum key distribution scheme with intrinsic stabilization, enabling secure communication over long distances with high stability and low error rates, suitable for real-world fiber networks.

Contribution

The authors propose a novel intrinsic-stabilization scheme using Michelson-Faraday interferometers that improves long-distance quantum key distribution stability and practicality.

Findings

Successful key exchange over 125 km with error rate below 6%

System remains stable and insensitive to environmental noise

Extended operational distance exceeds 150 km

Abstract

Quantum key distribution provides unconditional security for communication. Unfortunately, current experiment schemes are not suitable for long-distance fiber transmission because of instability or backscattering. We present a uni-directional intrinsic-stabilization scheme that is based on Michelson-Faraday interferometers, in which reflectors are replaced with 90 degree Faraday mirrors. With the scheme, key exchange from Beijing to Tianjin over 125 kilometers with an average error rate is below 6% has been achieved and its limited distance exceeds 150 kilometers. Experimental result shows the system is insensitive to environment and can run over day and night without any break even in the noise workshop.