Improved method of decoy state quantum key distribution based with HPCS sources

Based on the heralded pair-coherent states sources, the Vacuum+Weak decoy state protocol focused on BB84 is presented. Combining the passive decoy state method and the active decoy state method, we use the triggered and nontriggered components to estimate the fraction of single-photon counts and quantum bit-error rate of single-photon and to generate the secure key. From the simulation results of the final key rate over the distance, which shows that our method improve the QKD performance and obtain higher key generation rate than that of the active decoy states method.