QUANTUM CRYPTOGRAPHY DEVICE Russian patent published in 2019 - IPC H04L9/08 H04B10/25 G06F21/60 

FIELD: cryptography.

SUBSTANCE: invention relates to the field of quantum cryptography. Device for quantum cryptography includes transmitting and receiving parts separated by a communication line, the transmitting part comprises a radiation source, an intensity modulator and a phase modulator, transmitting part is configured to generate at the output a pair of pulses with orthogonal states and identical time intervals between pulses, wherein states from different pairs are not orthogonal, and polarization of all pulses is identical, receiving part comprises fiber circulator, symmetric fiber beam splitter, first and second Faraday mirrors and first and second detectors, input of receiving part is connected to input of fiber circulator, first output of which is fiber-connected to first input of fiber-optic beam splitter, and second output is fiber-connected to first detector, second input of fiber-optic splitter is fiber-connected to second detector, and first and second outputs of fiber-optic splitter are fiber-connected to first and second Faraday mirrors, respectively. Lengths of the first and second optical paths on the first and second outputs of the fiber beam splitter are different and selected so that during propagation of pulses from the output of the fiber beam splitter to the corresponding faraday mirror and back along the first and second optical paths between them there was a stroke difference corresponding to time interval between two pulses of the pair.

EFFECT: eliminating the need to adjust polarization state at the output of the communication line and in the receiving part while simplifying the design of the receiving part.

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