Improved Parameter Estimation Methods in the Post-Processing Phase of Quantum Key Distribution

In the post-processing phase of Quantum Key Distribution (QKD), a crucial step involves the parameter estimation of the initial key. Among various techniques, the group parity check method stands out as a prevalent approach for parameter estimation. This method operates by segmenting the received key into groups and applying parity checks within each group to estimate the bit error rate. Theoretically, this method can achieve high precision estimation with minimal information leakage compared to traditional random sampling methods. However, the practical efficiency and estimation accuracy of this method are contingent upon the group size and the statistical properties of the errors, which sometimes may not yield superior results relative to conventional methods. This paper introduces an enhanced group parity check method, which incorporates an additional parity code comparison and employs a dynamic group strategy, effectively reducing information leakage in subsequent error correction steps caused by erroneous estimations. Experimental results demonstrate that the proposed parameter estimation method can more accurately estimate and correct errors occurring during the QKD physical process and dynamically optimize the key generation process according to actual communication conditions.