Zhengchao Wei

Reconciliation is an important step to correct errors in Quantum Key Distribution (QKD). In QKD, after comparing basis, two legitimate parties possess two correlative keys which have some difference and they could obtain identical keys through reconciliation. In our paper, we present a new rate compatible reconciliation scheme based on Row Combining with Edge Variation (RCEV) Low Density Parity Check (LDPC) codes which could change code rate adaptively in noisy channel where error rate may changes with time. Our scheme is easy to implement and could get good efficiency compared to existing schemes. Meanwhile, due to the inherent structure we use, the new scheme not only save memory space remarkably but also simplify the decoder architecture and accelerate the decoding.

We propose a quantum key distribution scheme that combines a biased basis choice with the decoy-state method. In this scheme, Alice sends all signal states in the Z basis and decoy states in the X and Z basis with certain probabilities, and Bob measures received pulses with optimal basis choice. This scheme simplifies the system and reduces the random number consumption. From the simulation result taking into account of statistical fluctuations, we find that in a typical experimental setup, the proposed scheme can increase the key rate by at least 45% comparing to the standard decoy-state scheme. In the postprocessing, we also apply a rigorous method to upper bound the phase error rate of the single-photon components of signal states.