Measurement-Device-Independent Twin-Field Quantum Key Distribution

TL;DR

This paper clarifies the security and measurement-device-independent nature of twin-field quantum key distribution (TFQKD), demonstrating its advantages and proposing an experimental setup for practical implementation.

Contribution

It shows that TFQKD can be viewed as an MDI-QKD with single-photon Bell state measurement, enabling the use of existing security proofs and facilitating experimental realization.

Findings

TFQKD can be regarded as MDI-QKD with single-photon Bell state measurement.

Universal security proof theories apply directly to TFQKD.

Proposed a feasible experimental scheme for demonstration.

Abstract

The ultimate aim of quantum key distribution (QKD) is improving the performance of transmission distance and key generation speed. Unfortunately, it is believed to be limited by the secret-key capacity of quantum channel without quantum repeater. Recently, a novel twin-field QKD (TFQKD) [Nature 557, 400 (2018)] is proposed to break through the limit, where the key rate is proportional to the square-root of channel transmittance. Here, by using the vacuum and one-photon state as a qubit, we show that the TF-QKD can be regarded as a measurement-device-independent QKD (MDI-QKD) with single-photon Bell state measurement. Therefore, the MDI property of TF-QKD can be understood clearly. Importantly, the universal security proof theories can be directly used for the TF-QKD, such as BB84, six-state and reference-frame-independent schemes. Furthermore, we propose a feasible experimental scheme for the proof-of-principle experimental demonstration.