Anti-polarization-disturbance phase encoding quantum key distribution system

Abstract

The invention relates to an anti-polarization-disturbance phase encoding quantum key distribution system which comprises a sending module and a receiving module. The receiving module comprises an optical fiber circulator, a first polarization beam splitter, a first Mach-Zehnder interferometer, a second polarization beam splitter, a first single-photon detector and a second single-photon detector.The output end of the sending module is connected with the input end of the optical fiber circulator; one output end of the optical fiber circulator is connected with the input end of the first single-photon detector. The other output end of the optical fiber circulator is in bidirectional connection with the input end of the first polarization beam splitter. Two output ends of the first polarization beam splitter are correspondingly and bidirectionally connected with two ends of the first Mach-Zehnder interferometer. The other two ends of the first Mach-Zehnder interferometer are connected with the input end of the second polarization beam splitter. The output end of the second polarization beam splitter is connected with the input end of the second single-photon detector. According to the invention, the influence of channel polarization disturbance on the distribution system is eliminated, and the stability of the distribution system is improved.

Description

technical field [0001] The invention belongs to the field of optical fiber quantum key distribution systems, and in particular relates to a polarization-disturbance-resistant phase-coded 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, research...

AI Technical Summary

Problems solved by technology

One of them is active polarization compensation. A polarization compensation module is added at the receiving end, and polarization tracking and compensation are performed through feedback control. This type of solution will increase the complexity of the system, consume time and resources, and have a high bit error rate.

The other type is passive compensation of the polarization state, such as the Plug-and-play (plug and play) round-trip quantum key distribution system, which uses the Faraday mirror to rotate the polarization state of the incident light by 90 degrees to offset the optical fiber channel's effect on photons. Polarization state, so as to ensure the stability of the system; however, due to its back-and-forth structure, this scheme has security risks and is vulnerable to Trojan horse attacks, and the operating frequency of the system is limited, and the Raman scattering effect of the optical fiber will also increase. System noise

Another solution is to add a depolarizer at the sending end to randomize the polarization state before photons enter the fiber channel, which can eliminate the influence of fiber birefringence and environmental disturbance on the polarization state, and add a polarization splitter at the receiving end. Beamer polarizer can obtain stable interference results, but this solution will double the loss and reduce the efficiency of the system by half

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