Synchronization algorithm of quantum key distribution system with protection from unauthorized access

The two pass auto compensation quantum key distribution system (QKDS) with phase-encoded states of photons in synchronization mode are studied. The algorithm of synchronization QKDS, presupposing the division of the repetition period of the optical pulses on the time windows and the detection of the signal window are offered. The peculiarity of the algorithm is that it is implemented in the single-photon mode, increasing the security of synchronization mode. The second feature of the algorithm is that when equal numbers of accumulated pulses in two adjacent time windows, a decision for admission photon pulse in any of the windows, if the number of accumulated pulses in it exceeds the number of detected pulses in the other windows. In a certain algorithm in this case, both windows were “noises” that was the reason for missing the signal window. Modeling algorithm found that when the number of time windows from 2 to 1024, the difference of the limiting values of the probability does not exceed 3.34%. The requirements with respect to the duration of the time window and the photon momentum are formulated. It is shown that increasing the number of time windows from 2 to 1024 implies reducing the probability of less than 2% while maintaining the time of uncertainty in relation of emergence the photon pulse 512 times. An analytical expression for the calculation of the probability of correct detection of the signal time window in the proposed synchronization algorithm QKDS.