Enhancing Key Rates of QKD Protocol by Coincidence Detection

In theory, quantum key distribution (QKD) provides unconditional security; however, its practical implementations are susceptible to exploitable vulnerabilities. This investigation tackles the constraints in practical QKD implementations using weak coherent pulses. The conventional approach of using decoy pulses is improved by integrating it with the coincidence detection (CD) protocol. Additionally, an easy-to-implement technique is employed to compute asymptotic key rates for the protocol secure under specific photon number splitting (PNS) attacks. Furthermore, an experimental implementation of the protocol, where it is demonstrated that monitoring coincidences in the decoy state protocol leads to enhanced key rates under realistic experimental conditions, is carried out.