Extended single-photon entanglement-based phase-matching quantum key distribution

Twin-field quantum key distribution (TF-QKD) is a hot topic in the field of quantum information due to its potential to break the key rate linear bound. Among all the variants, the single-photon entanglement-based phase-matching QKD protocol (SEPM-QKD) has been proposed, which is an entangled version of TF-QKD. However, a significant defect of SEPM-QKD is that its key rate is much lower than other QKDs. In this paper, we proposed an extended SEPM-QKD protocol with the help of delocalized state measurement. The proposed scheme can be regarded as TF-QKD connected by a single-photon entanglement-based quantum repeater. A security proof based on entanglement purification protocol in wave-state space against all channel attacks has been presented. Violation of CHSH-type Bell’s inequality is used to test the delocalized quantum correlation of the source. The simulation results show that the key rate of extended SEPM-QKD has the same performance as phase-matching (PM)-QKD and TF-QKD, while the communication distance is almost twice that of them.