Research On Underwater Optical Quantum Channel And Quantum Key Distribution Network

Quantum information technology is an emerging frontier technology that is currently valued by all countries,and it will bring revolutionary changes to the fields of communication and information security,complex computing,and sensing.Quantum key distribution is based on the theory of quantum mechanics and has the security feature that it cannot be eavesdropped from the channel without being noticed.Quantum secure communication based on quantum key distribution and one-time encryption system can realize unconditional security of communication.In the actual quantum communication process,the characteristics of the quantum transmission channel will affect the performance of quantum communication,so it is necessary to study the transmission characteristics of the quantum channel.This paper mainly studies the transmission characteristics of underwater optical quantum channels and quantum key distribution networks.The thesis first introduces the research status of quantum channels and quantum key distribution networks,gives relevant basic theoretical knowledge,and typical protocols such as BB84,MDI-QKD,introduces the types of quantum noise channels,and summarizes the quantum key distribution network type and topology.Secondly,the optical quantum transmission characteristics of the seawater wireless optical channel and the underwater optical cable channel are studied,including the attenuation and polarization change of the seawater wireless optical channel,the absorption loss and scattering loss of the underwater optical cable channel,and the parametric modeling of polarization mode dispersion due to ellipticity,stress and bending.Numerical analysis results show that when the wavelength is 1.55μm,the loss caused by ultraviolet absorption can reach 0.084 d B/km,and the loss caused by infrared absorption is 0.020 d B/km;when the wavelength is 1.32μm,the typical values of birefringence caused by ellipticity,stress and bending are 0.113 rad/m,-4.137 rad/m and 0.19 rad/m respectively.Finally,the analysis method of polarization mode dispersion when multiple factors are acting simultaneously is given.Third,on the basis of studying the general architecture of quantum key distribution network,an underwater wireless/wired hybrid quantum key distribution network structure based on trusted relay is proposed,which can realize the quantum key distribution between underwater vehicles and onshore equipment,and is scalable.The architecture of the network is divided into quantum layer,control layer,and application layer.The operation process of the network is illustrated with examples,and the security,cost function of the network and the key rate of different links when the BB84 protocol is used for key distribution are analyzed.Finally,the content of the full text is summarized,and future research suggestions are given.