Closing the gap of secure quantum key rate with the Heralded Pair-Coherent States

1 Key Laboratory of Quantum Information, University of Science and Technology of China (CAS), Hefei 230026, China.2 Zheng Zhou Information and Technology Institute, Zhengzhou, Henan 450004, China(Dated: July 11, 2008)In this paper, we investigate the long-standing gap of quantum key rate between the Weak Co-herent Pulse (WCP) and Heralded Single Photon Sources(HSPS) implementation of quantum cryp-tographical protocol. We prove that, by utilizing the Heralded Pair Coherent State (HPCS) photonsources, such a gap can be actually filled in both BB84 and SARG quantum key distribution. Thus,a universal photon source which achieves the up-to-date optimal key rate for each transmissiondistance is obtained.