Re-pairing strategy for mode-pairing quantum key distribution

Abstract

Mode-pairing quantum key distribution (MP-QKD) leverages post-selection pairing strategy to achieve a balance between ease of implementation and high performance, establishing itself as a highly promising protocol in future QKD networks. However, the reliance on pairing strategies causes a considerable number of pulses to be excluded from parameter estimation and key generation, introducing inefficiencies and diminishing overall performance. In this study, we extend the original protocol by incorporating an active pairing strategy. This involves actively pairing clicking events that fall within the same phase slice, thereby generating new successful pairs and enabling the reutilization of previously discarded events. To validate the efficiency of our scheme, we conducted simulations of the three-intensity decoy-state MP-QKD protocol with the double-scanning method. The simulation results demonstrate significant advantages in both parameter estimation and final key generation. Therefore, this study provides valuable insights for advancing future MP-QKD experiments and applications.