More than Mbps secret key rate was demonstrated for continuous-variable quantum key distribution (CV-QKD) systems, but real-time postprocessing is not allowed, which is restricted by the throughput of the error correction decoding in postprocessing. In this paper, a high-throughput FPGA-based quasi-cyclic LDPC decoder is proposed and implemented to support Mbps real-time secret key rate generation for CV-QKD for the first time. A residual bit error correction algorithm is used to solve the problem of high frame errors rate (FER) caused by the limited precision of the decoder. Specifically, real-time high-speed decoding for CV-QKD systems with typical code rates 0.2 and 0.1 is implemented on a commercial FPGA, and two throughputs of 360.92Mbps and 194.65Mbps are achieved, respectively, which can support 17.97 Mbps and 2.48 Mbps real-time generation of secret key rates under typical transmission distances of 25km and 50km, correspondingly. The proposed method paves the way for high-rate real-time CV-QKD deployment in secure metropolitan area network.
@article{arxiv.2207.01860,
title = {High-throughput decoder of quasi-cyclic LDPC codes with limited precision for continuous-variable quantum key distribution systems},
author = {Chuang Zhou and Yang Li and Li Ma and Jie Yang and Wei Huang and Heng Wang and Yujie Luo and Francis C. M. Lau and Yong Li and Bingjie Xu},
journal= {arXiv preprint arXiv:2207.01860},
year = {2022}
}