Practical gigahertz quantum key distribution robust against channel disturbance

TL;DR

This paper presents a high-speed quantum key distribution system that automatically compensates for channel disturbances, enabling stable and secure communication over long fiber channels without active polarization adjustments.

Contribution

A novel Faraday-Sagnac-Michelson QKD system that automatically corrects channel polarization disturbances, enhancing practicality for real-world secure communication.

Findings

Achieved 99.35% interference fringe visibility over 24 hours.

Maintained a stable secure key rate of 306k bits/s over 7 days.

Operated effectively over 50 km fiber with 30-Hz polarization scrambling.

Abstract

Quantum key distribution (QKD) provides an attractive solution for secure communication. However, channel disturbance severely limits its application when a QKD system is transfered from the laboratory to the field. Here, a high-speed Faraday-Sagnac-Michelson QKD system is proposed that can automatically compensate for the channel polarization disturbance, which largely avoids the intermittency limitations of environment mutation. Over a 50-km fiber channel with 30-Hz polarization scrambling, the practicality of this phase-coding QKD system was characterized with an interference fringe visibility of 99:35% over 24 hours, and a stable secure key rate of 306k bits/s over 7 days without active polarization alignment.