Measurement-device-independent quantum key distribution based on Bell's inequality

TL;DR

This paper introduces two Bell's inequality-based measurement-device-independent quantum key distribution protocols, enhancing security against source-side attacks and demonstrating secure long-distance communication over 200 km.

Contribution

The paper presents two novel MDI-QKD protocols based on Bell's inequality, with one protocol not requiring perfect state characterization, improving security against source-side attacks.

Findings

Both protocols achieve secure quantum key distribution over 200 km.

The second protocol is robust against source-side attacks.

A new technique for estimating Bell's inequality violation is proposed.

Abstract

We propose two quantum key distribution (QKD) protocols based on Bell's inequality, which can be considered as modified time-reversed E91 protocol. Similar to the measurement-device-independent quantum key distribution (MDI-QKD) protocol, the first scheme requires the assumption that Alice and Bob perfectly characterize the encoded quantum states. However, our second protocol does not require this assumption, which can defeat more known and unknown source-side attacks compared with the MDI-QKD. The two protocols are naturally immune to all hacking attacks with respect to detections. Therefore, the security of the two protocols can be proven based on the violation of Bell's inequality with measurement data under fair-sampling assumption. In our simulation, the results of both protocols show that long-distance quantum key distribution over 200 km remains secure with conventional lasers in the asymptotic-data case. We present a new technique to estimate the Bell's inequality violation, which can also be applied to other fields of quantum information processing.