Journal Article

Rate compatible reconciliation for continuous-variable quantum key distribution using Raptor-like LDPC codes

Zhou, Chao, Wang, XiangYu, Zhang, ZhiGuo, Chen, ZiYang, Yu, Song, Guo, Hong

2021

Overview

In the practical continuous-variable quantum key distribution (CV-QKD) system, the postprocessing process, particularly the error correction part, significantly impacts the system performance. Multi-edge type low-density parity-check (MET-LDPC) codes are suitable for CV-QKD systems because of their Shannon-limit-approaching performance at a low signal-to-noise ratio (SNR). However, the process of designing a low-rate MET-LDPC code with good performance is extremely complicated. Thus, we introduce Raptor-like LDPC (RL-LDPC) codes into the CV-QKD system, exhibiting both the rate compatible property of the Raptor code and capacity-approaching performance of MET-LDPC codes. Moreover, this technique can significantly reduce the cost of constructing a new matrix. We design the RL-LDPC matrix with a code rate of 0.02 and easily and effectively adjust this rate from 0.016 to 0.034. Simulation results show that we can achieve more than 98% reconciliation efficiency in a range of code rate variation using only one RL-LDPC code that can support high-speed decoding with an SNR less than −16.45 dB. This code allows the system to maintain a high key extraction rate under various SNRs, paving the way for practical applications of CV-QKD systems with different transmission distances.

• Publisher: Science China Press,Springer,Springer Nature B.V
• Subject: Astronomy / Classical and Continuum Physics / Codes / Continuity (mathematics) / Decoding / Error correcting codes / Error correction / Low density parity check codes / Observations and Techniques / Physics / Physics and Astronomy / Quantum cryptography / Reconciliation / Signal to noise ratio