Reconciliation for CV-QKD using globally-coupled LDPC codes*

Abstract

Reconciliation is a necessary step in postprocessing of continuous-variable quantum key distribution (CV-QKD) system. We use globally coupled low-density parity-check (GC-LDPC) codes in reconciliation to extract a precise secret key from the raw keys over the authenticated classical public channel between two users. GC-LDPC codes have excellent performance over both the additive Gaussian white noise and binary-erasure channels. The reconciliation based on GC-LDPC codes can improve the reconciliation efficiency to 95.42% and reduce the frame error rate to 3.25 × 10–3. Using distillation, the decoding speed can achieve 23.8 Mbits/s and decrease the cost of memory. Given decoding speed and low memory usage, this makes the proposed reconciliation method viable approach for high-speed CV-QKD system.

Rate-Compatible LDPC Codes for Continuous-Variable Quantum Key Distribution in Wide Range of SNRs Regime

“…It is mainly caused by two reasons: the defect of error correcting code and decoding algorithm; the unadaptable check matrix led by the changing of SNR. The FER caused by the defect of error correcting code and decoding algorithm can be reduced to , which is far lower than the FER led by the latter reason [ 28 ]. Therefore, we only take the latter reason into account.…”

Low-complexity adaptive reconciliation protocol for continuous-variable quantum key distribution

“…The proposed protocol replaces the LDPC precoding in Raptor codes with syndrome calculations, where the syndrome securely carries the message of secret keys used for message-passing LDPC decoding. In other words, the proposed protocol uses a random binary sequence of length l as the input to the LT transform, while the previous protocol uses a random binary sequence of length k encoded by LDPC codes as the input to the LT transform, k < l [24][25][26][27][28]. Therefore, the length of the raw key in the proposed protocol is longer.…”

Performance analysis of quantum key distribution using polarized coherent-states in free-space channel

“…Due to the non-cloning theorem, [1,2] quantum key distribution (QKD) technology has become a hot topic in the field of cryptography. Continuous-variable (CV) QKD [3][4][5][6][7] has attracted a lot of attention in the last few years, mainly because it is compatible with existing standard telecom components and can be used in common environments. [8][9][10] In recent decades, much experimental progress of CV-QKD has been made not only in optical-fiber links [11][12][13][14][15][16][17][18] but also in free-space channel.…”