Experimental measurement-device-independent type quantum key distribution with flawed and correlated sources

TL;DR

This paper demonstrates a secure quantum key distribution protocol resilient to source flaws using the reference technique, with experimental validation achieving practical secure key rates over significant distances.

Contribution

It introduces a finite-key security proof for measurement-device-independent QKD with flawed sources, supported by experimental demonstration.

Findings

Achieved a secure key rate of 253 bps over 20 dB loss

Improved secure transmission distance compared to previous protocols

Validated the protocol's practicality through experimental implementation

Abstract

The security of quantum key distribution (QKD) is severely threatened by discrepancies between realistic devices and theoretical assumptions. Recently, a significant framework called the reference technique was proposed to provide security against arbitrary source flaws under current technology such as state preparation flaws, side channels caused by mode dependencies, the Trojan horse atttacks and pulse correlations. Here, we adopt the reference technique to prove security of an efficient four-phase measurement-device-independent QKD using laser pulses against potential source imperfections. We present a characterization of source flaws and connect them to experiments, together with a finite-key analysis against coherent attacks. In addition, we demonstrate the feasibility of our protocol through a proof-of-principle experimental implementation and achieve a secure key rate of 253 bps with a 20 dB channel loss. Compared with previous QKD protocols with imperfect devices, our study considerably improves both the secure key rate and the transmission distance, and shows application potential in the practical deployment of secure QKD with device imperfections.