Polarization-independent phase codec and quantum key distribution system

Abstract

The invention relates to a polarization-independent phase codec. Two interfaces of a circulator are respectively connected with a first single-photon detector and a first polarization beam splitter, and a light outlet of the first polarization beam splitter is respectively connected with a light inlet of a third polarization-maintaining beam splitter through a fast axis and a slow axis of a polarization-maintaining optical fiber, a light outlet of the third polarization-maintaining beam splitter is connected with a light inlet of a second polarization beam splitter through a fast axis and a slow axis of the polarization-maintaining optical fiber respectively, a second phase modulator is connected between one path of light outlet of the second polarization beam splitter and an entrance, andone path of light outlet of the first polarization beam splitter is connected with a second single-photon detector. The invention further provides a quantum key distribution system. Compared with theprior art, the requirement for the sending end is low, the structure of the receiving end is simple, the detector comprises H and V components, the interference result cannot be affected by the change of the incident polarization state, polarization is irrelevant, the influence of channel polarization disturbance on the system can be resisted, the bit error rate is reduced, and the key generationrate is increased.

Description

technical field [0001] The invention relates to the technical field of quantum polarization encoding, in particular to a polarization-independent phase encoding decoder and a quantum key distribution system. Background technique [0002] The optical fiber quantum key distribution system generally uses single-mode optical fiber as the transmission channel, but due to the inherent birefringence effect of the optical fiber channel, the polarization state of the photon will change during the transmission process, and will change with the change of the external environment, so that The polarization state of photons as they enter the receiving end is unpredictable. Therefore, the traditional quantum key distribution system based on the double unequal arm Mach-Zehnder interference ring scheme has poor stability and is susceptible to environmental interference. [0003] In order to improve the stability and practicability of the quantum key distribution system, researchers have pro...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a polarization-independent phase encoder and decoder and a quantum key distribution system to solve the security risks of som

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