Phase-polarization multi-freedom-degree-modulation QKD network system and method

Abstract

The invention relates to a phase-polarization multi-freedom-degree-modulation QKD (quantum key distribution) network system and method. The system comprise an Alice transmitting end, a WDM (wavelength division multiplexing) unit and a multi-user Bob end, wherein the Alice end is connected with the multi-user Bob end through the WDM unit, and the Alice end comprises a multi-wavelength laser generating device, an attenuator, a first polarization beam splitter, a first beam combiner, a phase modulator, a first polarization controller and a second polarization controller; the WDM unit comprises a wavelength selecting device; the multi-user Bob end comprises a plurality of unit Bob user ends for receiving different wavebands, and each unit Bob user end comprises a second polarization controller, a third polarization controller, a fourth polarization controller, a third polarization beam splitter, a fourth polarization beam splitter, a second beam combiner, a third beam combiner, a first photon detector, a second photon detector, a third photon detector and a fourth photon detector. The QKD network system has the advantages that one-to-many quantum key sharing, information transmission capacity is expanded effectively, and the system is applicable to a phase-polarization multi-freedom-degree-modulation QKD scheme and other QKD schemes.

Description

technical field [0001] The invention relates to the technical field of quantum secure communication and optical fiber communication in the communication field, in particular to a phase polarization multi-degree-of-freedom modulation QKD network system and a key distribution method. Background technique [0002] At present, quantum signal modulation generally adopts single-degree-of-freedom modulation such as polarization, phase, frequency, and intensity. The polarization modulation of optical signals refers to the loading of information by adjusting the polarization direction of light. Usually, two linear polarization states of photons are used for encoding. Since the polarization state of light is easily affected by factors such as stress birefringence and polarization mode dispersion in the optical fiber during transmission, as well as environmental interference, polarization compensation or other methods are generally required. Methods to ensure polarization stabilizatio...

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Problems solved by technology

[0004] In 2006, "Phase Modulation Polarization State Quantum Encoders and Decoders and Their Applications" published by Tang Zhilie and others proposed a new quantum key distribution method for phase modulation polarization encoding. Although it has high stability, However, the photon utilization rate of the quantum secure communication of the six-state quantum encoder and decoder is relatively low.

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