Plug-and-play sending-or-not-sending twin-field quantum key distribution.

Twin-field quantum key distribution (TF-QKD) is a new extraordinary QKD protocol, which can overcome the fundamental rate-distance limit without quantum repeaters. Moreover, its variant, the sending-or-not-sending twin-field quantum key distribution (SNS-QKD) protocol, can both tolerate large misalignment error and have a higher key rate; however, the light source is assumed to be the trusted one in the original SNS protocol. In this paper, we propose a more practical SNS-QKD protocol with plug-and-play architecture, named P & P SNS-QKD protocol. We present the framework of P & P SNS-QKD protocol and analyze the tight bound of its key rate with the four-intensity decoy-state method. The proposed protocol can avoid the careful adjustments, and the control of the system and the numerical simulations results show that the proposed protocol has a close key generation rate to that of the original SNS-QKD. Besides, the proposed protocol still maintains a high tolerance for misalignment errors even if the source is unknown and untrusted. [ABSTRACT FROM AUTHOR]