QKD metropolitan area network system based on Sagnac loop and key distribution method thereof

Abstract

The invention provides a QKD metropolitan area network system based on a Sagnac loop and a key distribution method thereof. The system comprises an Alice control end, a Sagnac transmission backbone loop, an optical cross-connect OXC as a backbone node, and an access net NETmn comprising n Bob user sides. The Alice control end comprises a multi-wavelength pulse laser generation device, a wavelengthselection switch, a circulator, a single photon detector group, a coupler and a phase modulator PMA. The Bob user sides of the access net comprise variable optical attenuators, pulse delay devices, phase modulators PMBs and reflection mirrors. The OXC is taken as the backbone node of the Sagnac loop. Even if a fault occurs in a certain node, the operation of a whole network is not influenced. According to the key distribution method, a decoy state protocol is employed, a key generation rate is improved, and the relatively long transmission distance is increased.

Description

technical field [0001] The invention relates to the field of fusion of quantum information technology and quantum classical optical fiber communication, and more specifically relates to a Sagnac ring-based QKD metropolitan area network system and a key distribution method thereof. Background technique [0002] Quantum information is an emerging interdisciplinary subject formed by the close combination of quantum mechanics and classical information theory. It is a research hotspot in the field of physics, and quantum communication is a research hotspot in the field of quantum information. Quantum communication refers to communication using the basic principles or characteristics of quantum mechanics. The carrier of its information is microscopic particles. The quantum uncertainty theorem and the non-cloning theorem guarantee the unconditional security of quantum secure communication theory. [0003] In quantum communication technology, the point-to-point two-party quantum key...

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Problems solved by technology

In this scheme, the pulse generated by the laser at the same time is still a single wavelength pulse, which can only serve a single user, which causes the dilemma that multiple users cannot work at the same time, and is essentially one-to-one

[0005] Both of the above two solutions largely limit the increase in the number of users, and the expansion of users leads to problems such as a decrease in the key generation rate.

Later, although the number

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