Field Test of Measurement-Device-Independent Quantum Key Distribution

TL;DR

This paper reports a field test of a high-speed, automatic measurement-device-independent quantum key distribution system over 30 km fiber, demonstrating practical secure key rates and advancing quantum network security.

Contribution

Developed an automatic, high-clock-rate MDIQKD system and successfully tested it in the field over 30 km fiber, achieving a record secure key rate for practical deployment.

Findings

Achieved a secure key rate of 16.9 bps in the field test.

Demonstrated system stability with automatic calibration.

Validated the feasibility of practical quantum networks.

Abstract

A main type of obstacles of practical applications of quantum key distribution (QKD) network is various attacks on detection. Measurement-device-independent QKD (MDIQKD) protocol is immune to all these attacks and thus a strong candidate for network security. Recently, several proof-of-principle demonstrations of MDIQKD have been performed. Although novel, those experiments are implemented in the laboratory with secure key rates less than 0.1 bps. Besides, they need manual calibration frequently to maintain the system performance. These aspects render these demonstrations far from practicability. Thus, justification is extremely crucial for practical deployment into the field environment. Here, by developing an automatic feedback MDIQKD system operated at a high clock rate, we perform a field test via deployed fiber network of 30 km total length, achieving a 16.9 bps secure key rate. The result lays the foundation for a global quantum network which can shield from all the detection-side attacks.