A new scheme on improving the performance of the quantum key distribution with two-intensity weak coherent light

Abstract

In this paper, we propose a new scheme on implementing the quantum key distribution with two-intensity weak coherent light and compare its performance with other existing methods. Through numerical simulations, we demonstrate that our new scheme can exceed almost all other existing decoy-state methods, e.g., the standard three-intensity decoy-state method and the usual passive decoy-state method, both in the transmission distance and in the final key generation rate, approaching very closely to the ideal case of using an infinite number of decoy states. Besides, we also consider the finite-size key effect. We demonstrate that under current experimental conditions, even when taking statistical fluctuation into account, a quite high key generation rate can still be obtained at very long transmission distance by applying our new scheme.