FIBRE-OPTIC SYSTEM AND METHOD FOR QUANTUM KEY DISTRIBUTION WITH UNTRUSTED CENTRAL NODE Russian patent published in 2025 - IPC H04L9/08 H04B10/70 

FIELD: physics.

SUBSTANCE: invention relates to quantum key distribution with untrusted central node (UCN). Transmitting unit comprises a continuous laser source, a phase modulator, an intensity modulator, beam splitter connected by one arm with optical power meter, and by the other one – with system of attenuators, optical isolator, band-pass optical filter, adjustable optical attenuator; UCN contains a synchrolaser, two band-pass filters, polarization controllers, an adjustable optical delay line, beam splitter with built-in polariser, which is connected through beam splitters to four detectors of single photons, providing registration of Bell states |Ψ^-〉 and |Ψ⁺〉.

EFFECT: high rate of generating quantum keys due to an optical circuit which enables measurements of both Bell states, as well as reduced requirements for the value of the mutual coherence of lasers and high visibility of interference by increasing the repetition rate of laser pulses.

2 cl, 4 dwg