Experimental measurement-device-independent quantum key distribution

TL;DR

This paper demonstrates a practical measurement-device-independent quantum key distribution system that achieves secure communication over 50 km fiber, immune to detection attacks and source imperfections, advancing quantum cryptography towards real-world application.

Contribution

Developed a high-efficiency, low-noise up-conversion single-photon detector integrated into an MDI-QKD system, ensuring security against detection and source attacks in practical settings.

Findings

Generated over 25 kbit secure key over 50 km fiber

Implemented decoy-state method to counter source attacks

Achieved immunity to detection hacking strategies

Abstract

Throughout history, every advance in encryption has been defeated by advances in hacking with severe consequences. Quantum cryptography holds the promise to end this battle by offering unconditional security when ideal single-photon sources and detectors are employed. Unfortunately, ideal devices never exist in practice and device imperfections have become the targets of various attacks. By developing up-conversion single-photon detectors with high efficiency and low noise, we build up a measurement-device-independent quantum key distribution (MDI-QKD) system, which is immune to all hacking strategies on detection. Meanwhile, we employ the decoy-state method to defeat attacks on non-ideal source. By closing the loopholes in both source and detection, our practical system, which generates more than 25 kbit secure key over a 50-km fiber link, provides an ultimate solution for communication security.