Practical decoy state quantum key distribution with finite resource

In this paper, we consider the controllably secure quantum key distribution (QKD) with coherent source, i.e., the practical decoy state QKD with finite resource is studied within the scope of some controllable security parameters. Our simulation shows the controllably secure QKD is more resource-consuming compared with the practical decoy QKD with relatively statistical fluctuation. However, further numerically solutions show that both protocols agree well with each other in the asymptotic limit, where the resource is large enough but not infinite. Our work shows the dark counts will contribute apparently to the transmission distance when communication distance approaches to the asymptotic limit. It also shows that both the secure transmission distance and the rate of the secure final key can be increased apparently when the security estimation parameters are not fixed but numerically optimized.