Recent advances on quantum key distribution overcoming the linear secret key capacity bound

TL;DR

This paper reviews recent progress in quantum key distribution, especially twin-field protocols, which surpass traditional capacity limits and enable secure long-distance communication through theoretical and experimental advancements.

Contribution

It provides a comprehensive survey of recent developments in twin-field QKD, including security proofs, realistic condition analyses, and experimental demonstrations.

Findings

Security proofs for phase-matching QKD protocols

Theoretical analyses under realistic conditions

Recent experimental demonstrations of TF-QKD

Abstract

A crucial goal for quantum key distribution (QKD) is to transmit unconditionally secure keys over long distances. Previous studies show that the key rate of point-to-point QKD is limited by a secret key rate capacity bound, and higher key rates would require quantum repeaters. In 2018, the seminal twin-field (TF) QKD protocol was proposed to provide a remarkable solution to overcoming the linear secret key capacity bound. This article presents an up-to-date survey on recent developments in this area, including the security proofs of phase-matching QKD and other TF-QKD type protocols, the theoretical examinations of these protocols under realistic conditions, and the recent experimental demonstrations.