Synchronization protocol for MDI-QKD systems

Commercial fiber quantum key distribution systems require the implementation of a protocol for synchronizing the frequency synthesizers of the transmitter and receiver nodes. Frequency mismatch may be due to temperature fluctuations, mechanical effects and imperfections in the technological processes. In this work, an algorithm for automatically adjusting Alice's and Bob's frequency to Charlie's frequency is proposed. After optimizing the algorithm parameters, it was tested on optical lines of different lengths.