Polarization compensation for entanglement-based quantum key distribution.

In quantum key distribution (QKD) systems using polarization entanglement, channel polarization perturbations significantly compromise both efficiency and security. To address the slow response and instability of current entanglement-based polarization compensation techniques for entanglement-based quantum key distribution, we propose a polarization compensation scheme based on an adaptive gradient descent algorithm. The system's performance is tested over a 10 km single-sided fiber channel. Results show that this scheme maintains long-term stability of the polarization state under both random and periodic perturbations. The average compensation time is 248 ms, with an entanglement source average visibility of 83.43% and an average quantum error rate of 8.28%. This method effectively mitigates polarization perturbation in entanglement-based quantum key distribution (QKD). These results are pivotal for the development of long-distance, multi-node quantum communication networks.