The performance analysis of quantum key distribution based on an irregular air-water interface

The effect of the irregular air-water interface on the performance of the down-link quantum key distribution from the air to the sea is studied. Based on the analysis of the relationship between the incident angle and the quantum bit error rate, the air-water interface model with wind speed is adopted, the influence of the wind speed on the incident angle of the photon is discussed, the relationship between the expected value of quantum bit error rate and the wind speed is deduced. Numerical simulation shows that the quantum bit error rate of the irregular air-water interface is related to the incident angle and the wind speed. If the incident angle is improved, the quantum bit error rate will increase, limiting the incident angle shall not exceed 40°. And the actual incident angle will improve with the wind speed increasing. We find that when the original incident angle is 10° and the wind speed is less than 10m/s, the maximum actual incident angle do not exceed 40°, which is advantageous to the quantum key distribution.