Novel Reconciliation Protocol Based on Spinal Code for Continuous-variable Quantum Key Distribution
This work addresses the need for efficient and adaptive reconciliation in long-distance CV-QKD systems, making them easier and more stable, though it appears incremental as it builds on existing reconciliation methods.
The paper tackles the problem of adaptive reconciliation in continuous-variable quantum key distribution by proposing a novel rateless protocol based on spinal code, achieving reconciliation efficiency around 95% over a wide SNR range and up to 96.5% at extremely low SNRs.
Reconciliation is a crucial procedure in post-processing of continuous variable quantum key distribution (CV-QKD) system, which is used to make two distant legitimate parties share identical corrected keys. The adaptive reconciliation is necessary and important for practical systems to cope with the variable channel. Many researchers adopt the punctured LDPC codes to implement adaptive reconciliation. In this paper, a novel rateless reconciliation protocol based on spinal code is proposed, which can achieve a high-efficiency and adaptive reconciliation in a larger range of SNRs. Due to the short codes length and simple tructure, our protocol is easy to implement without the complex codes designs of fixed rate codes, e.g., LDPC codes. Meanwhile, the structure of our protocol is highly parallel, which is suitable for hardware implementation, thus it also has the potential of high-speed hardware implementation. Besides, the security of proposed protocol is proved in theory. Experiment results show that the reconciliation efficiency maintains around 95% for ranging SNRs in a larger range (0,0.5), even exceeds 96.5% at extremely low SNR (<= 0.03) by using this novel scheme. The proposed protocol makes the long-distance CV-QKD systems much easier and stable to perform a high-performance and adaptive reconciliation.