CONTROLLING METHOD OF THE INTERFERENCE IMAGE IN A SINGLE-PASS SYSTEM OF QUANTUM CRYPTOGRAPHY Russian patent published in 2018 - IPC H04L9/08 G06F21/72 

FIELD: cryptography.

SUBSTANCE: invention relates to the field of quantum cryptography. Method consists in generating a random sequence of zeros and ones using a random number generator in the transmitting part, generate on the basis of a sequence of zeros and ones a sequence of quasi-one-photon states in the transmitting part, divide each quasi-one-photon state by means of the interferometer to a pair of spatially separated quasi-one-photon coherent states, transmit the obtained spatially separated quasi-one-photon coherent states from the transmitting part to the receiving part using a communication link, take spatially separated quasi-one-photon coherent states in the receiving part, an interference pattern is obtained from the spatially spaced quasi-one-photon coherent states at the output of the interferometer of the receiving part, register a sequence of quasi-one-photon states after passing the interferometer of the receiving part in the photodetector block in the form of a sequence of zeros and ones depending on the visibility of the obtained interference pattern for each quasi-one-photon state, determining an error signal in the processing unit of the receiving part based on comparing the received and transmitted sequences of zeros and ones, while as the error signal a quantity proportional to the number of mismatches in the positions of the received and transmitted sequences of ones and zeros is applied, and adjust the visibility of the interference pattern obtained at the output of the interferometer of the receiving part by compensating for the relative path difference in the interferometer of the receiving part based on the received error signal.

EFFECT: excluding the interruption of key transfer in the quasi-one-photon state for controlling the interference pattern.

1 cl, 2 dwg