Quantum key distribution system irrelevant to polarization coding measurement equipment

Abstract

The invention provides a quantum key distribution system irrelevant to polarization coding measurement equipment, which comprises a measurement end Charlie, an Alice reciprocating coding module and a Bob reciprocating coding module, and is characterized in that the measurement end Charlie is composed of a pulse laser, a Bell state measurement device and an orthogonal polarization pulse beam splitting and combining module; the Bell state measurement device comprises a beam splitter BS, a circulator CIR, a first polarization beam splitter PBS1, a second polarization beam splitter PBS2 and four single photon detectors SPD. The orthogonal polarization pulse beam splitting and combining module is provided with a first port, a second port, a third port and a fourth port. Compared with the prior art, the quantum key distribution system irrelevant to the polarization coding measurement equipment only uses a single laser combined with a reciprocating structure, can eliminate the problem that the frequencies of two lasers are inconsistent, can automatically compensate the channel polarization change, realizes stable preparation and transmission of a polarization state, does not need to adopt any active compensation module, the complexity of the system is reduced, and the stability and practicability of the system are improved.

Description

technical field [0001] The invention relates to the technical field of quantum polarization coding, in particular to a quantum key distribution system independent of polarization coding measurement equipment. Background technique [0002] The proposal of the measurement-device-independent quantum key distribution protocol (measurement-device-independent, MDI-QKD) removes the trustworthy requirements for the measurement end, can resist all attacks against the measurement end, and greatly improves the actual security of the system. [0003] In the MDI-QKD protocol, the legitimate communication parties Alice and Bob prepare quantum states respectively, and send them to the untrusted third party Charlie for Bell state measurement, which is equivalent to the time-reversal EPR quantum key distribution protocol. The core part of the Bell state measurement is the Hong-Ou-Mandel (HOM) interference, that is, the quantum states sent by Alice and Bob interfere at Charlie's beam splitter...

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Problems solved by technology

[0004] Conventional polarization-encoded MDI-QKD schemes inevitably require the use of polarization calibration modules when performing Bell state measurements, such as the document "Experimental demonstration of polarization encoding measurement-device-independent quantum key distribution." Phys. Rev. Lett.112 , 190503 (2014) and the document "Proof-of-principled demonstration of measurement-device-independent quantum key distribution based on intrinsically stable polarization-modulated units." Optics express 28.8 (2020): 10772-10782 adopted the scheme, Alice and Bob respectively Independent lasers are used to generate 4 stable polarization states, but the polarization states become random after passing through the fiber channel, requiring active polarization compensation, and there are problems with inconsistent wavelengths

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