Polarization multiplexing bidirectional quantum key distribution method and system

Abstract

The invention discloses a polarization multiplexing bidirectional quantum key distribution method. The method is suitable for a quantum communication system of non-polarization coding, an informationsending end of forward communication is defined as Alice, an information receiving end of forward communication is defined as Bob, Bob sends Alice and receives Alice as reverse communication, and in the method, two orthogonal polarizations are used for representing a carrier during forward communication and a carrier during reverse communication respectively. The invention further discloses a polarization multiplexing bidirectional quantum key distribution system. The Alice quantum emission device and the Alice quantum measurement device are respectively connected to a port 1 and a port 4 of the first polarization beam splitter PBS1; the Bob quantum emission device and the Bob quantum measurement device are respectively connected to a port 3 and a port 2 of the second polarization beam splitter PBS2; a port 2 of the first polarization beam splitter PBS1 and a port 1 of the second polarization beam splitter PBS2 are connected through an optical fiber channel. The system uses two orthogonal polarizations to represent a carrier during forward communication and a carrier during reverse communication respectively. Compared with an existing scheme using a circulator and a wavelength division multiplexer, the quantum communication rate is higher.

Description

technical field [0001] The invention relates to the field of quantum secure communication, and in particular provides a polarization multiplexing two-way quantum key distribution method and system. Background technique [0002] Quantum Key Distribution (Quantum Key Distribution, referred to as QKD) technology can generate unconditionally secure keys between communication parties, so it has attracted widespread attention. Since the BB84 program was put forward in 1984, various theoretical programs have been perfected day by day, and the technical realization has gradually matured and moved towards practical application. Quantum communication usually uses a one-way communication mode where the sender emits quantum signals and the receiver measures. With the development of Internet technology, people have higher and higher requirements for communication speed. If two-way communication is adopted, the rate of quantum communication can be effectively increased, the scope of use...

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Problems solved by technology

[0006] If the optical circulator is used to realize two-way quantum communication, the optical circulator will introduce polarization error and insertion loss, which will affect the quantum communication rate; if the wavelength division multiplexing bidirectional QKD scheme is used, in order to realize two-way communication, the spectral efficiency of one-way communication will be sacrificed and the number of wavelengths. At present, wavelengths in communication have become an important and scarce resource. The wavelengths that can be selected in quantum communication are limited. On the other hand, using different wavelengths for two-way communication will compress the number of wavelengths in one-way communication and affect quantum communication. If gratings are used for two-way communication, on the one hand, the cost of communication equipment will be greatly increased, and on the other hand, the stability of the system will be reduced, because the grating is a temperature-sensitive device, and the change of ambient temperature will seriously affect the working state of the grating. Similarly, using a grating also reduces spectral efficiency

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