SPIE Conference on Quantum and Nonlinear Optics

An efficient and high-speed two-stage decoding scheme for continuous-variable quantum key distribution system

Chuang Zhou, Yang Li, Li Ma, Yujie Luo, Wei Huang, Jie Yang, Jinlong Hu, Liangliang Zhang, Shuai Zhang, Bingjie Xu

Published Nov 27, 2022• 2 citations

Abstract

The throughput of error correction is the main bottleneck of continuous variable quantum key distribution (CV-QKD) postprocessing. Implementing the decoder of low-density parity-check (LDPC) codes based on FPGA with limited precision can improve the decoding throughput significantly. However, the limited precision on FPGA results in the existence of residual error-bits after decoding, which lowers the secret key rate and restricts the application of high-rate real-time CVQKD system. In this paper, an efficient decoding scheme is proposed to erase the residual error-bits and decrease the frame errors rate (FER), where the decoding process into two stages and some values of initial Log Likelihood Ratio (LLR) are adjusted according to the proposed principles before starting the second-stage decoding. For the rates 0.2 and 0.1 LDPC codes, numerical results demonstrate that the proposed decoding scheme decreases the FER obviously and the throughputs of 152.47Mbps and 88.32Mbps are achieved, which can be applied to support high-speed CV-QKD system under transmission distance of 25km and 50km respectively.

DOI: 10.1117/12.2643810

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