Photon-number-resolving decoy-state quantum key distribution (5 pages)

Xiongfeng Ma, Hoi-Kwong Lo, Yong Zhao +1 more

Yi Zhao, Hoi‐Kwong Lo, Xiongfeng Ma +3 more

Yong-Gang Tan

In this paper, security of practically decoy state quantum key distribution under fake state attack is considered. If quantum key distribution is insecure under this type of attack, decoy sources can not also provide it with enough security. Strictly analysis shows that Eve should eavesdrop with the aid of photon-number-resolving instruments. In practical implementation of decoy state quantum key distribution where statistical fluctuation is considered, however, Eve can attack it successfully with threshold detectors.

Roberto G. Pousa

Tomoyuki Horikiri, Takayoshi Kobayashi

Recently a long distance and high key rate quantum key distribution (QKD) has become possible by the idea of the decoy state method. We show that a longer distance QKD is possible by utilizing a heralded single photon source (utilizing spontaneous parametric down-conversion) as a source instead of a weak coherent pulse (WCP) as proposed in the original decoy state method. Moreover, the key rate is improved by utilizing a presently available photon number resolving detector as a trigger detector of the heralded single photon source and it is shown to approach the key rate of the WCP.

Xiongfeng Ma, Hoi‐Kwong Lo

Parametric down-conversion (PDC) sources can be used as triggered single photon sources in quantum key distribution (QKD). Recently, there have been several practical proposals of the decoy state QKD with triggering PDC sources. In this paper, we generalize the passive decoy state idea, originally proposed by Mauerer and Silberhorn. The generalized passive decoy state idea can be applied to cases where either threshold detectors or photon-number-resolving detectors are used. The decoy state protocol proposed by Adachi, Yamamoto, Koashi and Imoto (AYKI) can be treated as a special case of the generalized passive decoy state method. By simulating a recent PDC experiment, we compare various practical decoy state protocols with the infinite decoy state protocol and also compare the cases using threshold detectors and photon-number-resolving detectors. Our simulation result shows that with the AYKI protocol, one can achieve a key generation rate that is close to the theoretical limit of an infinite decoy state protocol. Furthermore, our simulation result shows that a photon-number-resolving detector appears to be not very useful for improving QKD performance in this case. Although our analysis is focused on QKD with PDC sources, we emphasize that it can also be applied to QKD setups with other triggered single photon sources.