Estimation of decoy state parameters for practical quantum key distribution

Qin Wang, Xiang‐Bin Wang, Guang‐Can Guo

We propose a practical decoy-state method with heralded single-photon source for quantum key distribution (QKD). In the protocol, three intensities are used and one can estimate the fraction of single-photon counts. The final key rate over transmission distance is simulated under various parameter sets. Due to the lower dark count than that of a coherent state, it is shown that a three-intensity decoy-state QKD with a heralded source can work for a longer distance than that of a coherent state.

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

Minal Lopes, Nisha Sarwade

Yang Wang, Wan‐Su Bao, Chun Hua Zhou +2 more

The decoy-state quantum key distribution (QKD) protocol has been widely used in commercial QKD systems. Several QKD field networks show its practicability and commercial prospects. Importantly, practical decoy-state QKD systems should be characterized with device imperfections. In this paper, for the case without intensity fluctuations, we present the parameter estimation based on the Chernoff bound for a practical decoy-state QKD protocol and compare performances of that based on Hoeffding's inequality and the Chernoff bound, respectively. Taking intensity fluctuations into consideration, we present the finite-key analysis with composable security against general attacks based on Azuma's inequality. Our numerical results show that the finite-key analysis based on the Chernoff bound is tighter than Hoeffding's inequality when the total number of transmitting signals $N<1\ifmmode\times\else\texttimes\fi{}{10}^{12}$. Moreover, the intensity fluctuations' influence is more obvious when the data size of total transmitting signals is small. Our results emphasize the importance of the stability of the intensity modulator as well as the accurate estimation of emitted pulse's intensity.

Lu Wang, Qin Dong, Rongzhen Jiao

Anton Sergeevich Trushechkin, Evgeniy O. Kiktenko, Aleksey K. Fedorov

Decoy-state quantum key distribution (QKD) is a standard tool for long-distance quantum communications. An important issue in this field is processing the decoy-state statistics taking into account statistical fluctuations (or ``finite-key effects''). In this work, we propose and analyze an option for decoy statistics processing, which is based on the central limit theorem. We discuss such practical issues as inclusion of the failure probability of the decoy-state statistical estimates in the total failure probability of a QKD protocol and also taking into account the deviations of the binomially distributed random variables used in the estimations from the Gaussian distribution. The results of numerical simulations show that the obtained estimations are quite tight. The proposed technique can be used as a part of post-processing procedures for industrial quantum key distribution systems.