Moscow Centre for Quantum Technologies, Moscow, Russia
Abstract:
Time synchronization is one of the most crucial issues that must be addressed in
developing quantum key distribution (QKD) systems. It not only lets the transmitter and the
receiver to assign a sequence number to each event and then do correct basis reconciliation, but
also allows to increase signal-to-noise ratio. Time synchronization in satellite communications
is especially complicated due to such factors as high loss, signal fading, and Doppler effect.
In this work, a simple, efficient, and robust algorithm for time synchronization is proposed.
It was tested during experiments on QKD between Micius, the world’s first quantum communi
cations satellite, and an optical ground station located in Russia. The obtained synchronization
precision lies in the range from 467 to 497ps. The authors compare their algorithm for time
synchronization with the previously used methods. The proposed approach can also be applied
to terrestrial QKD systems.
Keywords:quantum cryptography, quantum key distribution, satellite quantum communication, time synchronization.
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