High-dimensional quantum states key distribution (HD-QKD) can enable more than one bit per photon and tolerate more noise. Recently, a practical HD-QKD system based on time-phase states has provided a secret key at Mbps over metropolitan distances. For the purposes of further improving the secret key rate of a practical HD-QKD system, we make two main contributions in this work. Firstly, we present an improved parameter estimation for this system in the finite-key scenario based on the Chernoff bound and the improved Chernoff bound. Secondly, we analyze how the dimension $d$ affects the performance of the practical HD-QKD system. We present numerical simulations about the secret key rate of the practical HD-QKD system based on different parameter estimation methods. It is found that using the improved Chernoff bound can improve the secret key rate and maximum channel loss of the practical HD-QKD system. In addition, a mixture of the 4-level and 8-level practical HD-QKD system can provide better performance in terms of the key generation rate over metropolitan distances.
Supported by the National Basic Research Program of China under Grant No 2013CB338002, and the National Natural Science Foundation of China under Grant Nos 61505261, 61675235, 61605248 and 11304397.
- Ya-Hui Gan, Yang Wang, Wan-Su Bao, Ru-Shi He, Chun Zhou, Mu-Sheng Jiang. Finite-Key Analysis for a Practical High-Dimensional Quantum Key Distribution System Based on Time-Phase States[J]. CPL, 2019, 36(4): 40301-.