Analysis of one-decoy state SARG04 quantum cryptography protocol in the presence of afterpulse effect

The SARG04 quantum key distribution protocol can offer enhanced resilience to photon number splitting as contrasted with the BB84 protocol. In this paper, we propose a tight key analysis for the SARG04 protocol, considering the one-decoy method and investigating its performance under the influence of detector afterpulse. Our results reveal that increasing the block size can marginally boost both the secure key rate and the maximum achievable transmission distance. Importantly, we highlight that detector afterpulse is a pivotal element in practical implementation. Our analysis reveals that afterpulsing exerts a more substantial influence on the performance of the SARG04 protocol as opposed to the BB84 protocol. This underscores the necessity of considering afterpulse effects in down-to-earth quantum key distribution systems.