Abstract: In the process of satellite-ground quantum key distribution, under the condition of certain attenuation of space link, the sifted key of the system can be improved by increasing the quantum light emission frequency of the satellite. However, with the increase of the emission frequency of quantum light, the difficulty for the receiver to recover the detected time and location of quantum light is also increasing, which affects the quantum signal synchronization results. In order to ensure a good synchronization effect, a satellite-ground quantum signal synchronization scheme based on FPGA is realized by using high-precision time measurement and Doppler correction technology at 625 MHz of quantum light. With the use of the proposed scheme, the time precision of detection at the receiver reaches 52.4 ps, and the quantum bit error rate is about 1.78%. It is shown that the scheme can recover the time and position information of the detected quantum light, and can be used for the synchronization of the quantum signal transmission process.

Key words: quantum optics, time synchronization, high-precision time measurement, position restore; quantum key distribution