  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. We improve on the conventional
approach of using decoy pulses by integrating it with the coincidence detection
(CD) protocol. Additionally, we introduce an easy-to-implement algorithm to
compute asymptotic key rates for the protocol. Furthermore, we have carried out
an experimental implementation of the protocol, where we demonstrate that
monitoring coincidences in the decoy state protocol leads to enhanced key rates
under realistic experimental conditions.
