| Quantum communication is a new way of communication through quantum entanglement effect for information transmission.Based on the basic principles of quantum mechanics,the inalienability of the single photon and the unclonality of the quantum state ensure that information cannot be eavesdropped and cracked.Therefore,quantum communication is a research hotspot in the field of communication and information because of the advantages of high confidentiality and high security.At 1:40 in the early morning of August 16,2016,the first global quantum science experimental satellite "Mo-tse" was successfully launched at the Jiuquan satellite launch center in China.This is the first step in the use of quantum technology to build a global secure communication network.Quantum relay technology is the key technology to build global quantum communication network.Because the satellite and earth quantum satellite communication network is greatly influenced by the space environment,it is required that the influence of the space environment should be accurately studied.In order to ensure the reliability of the quantum communication,the various indexes of the satellite system should be adjusted adaptively according to the real-time detection of the space environment.However,the research on the influence of different plasma environments on the performance of quantum satellite communication has not been carried out so far.In this paper,the influence of plasma environment on the transmission of light quantum signals is studied by analyzing the characteristics of different plasma environment.The model of environmental characteristics to quantum satellite link attenuation and the quantitative relationship between the environmental characteristics and the performance parameters of the quantum satellite are emphatically discussed,which provide a rational research for the development of quantum communication in the future,which lays the foundation for further research on how to solve the problem of the attenuation of the quantum communication performance caused by the space environment.The innovation of this paper is divided into three parts:Firstly,according to the formation process of sporadic E layer,the relation between free electron density and height is obtained;Then the model of the attenuation of the quantum satellite link is established by the free electron density and the thickness of the sporadic E layer;according to the amplitude damping channel,the quantitative relationship between free electron density and channel capacity,entanglement fidelity,bit error rate and safe key generation rate is given.Secondly,according to the Mie scattering theory,the light scattering cross section of a single charged dust particle is obtained;Then the total extinction cross section is calculated by the particle concentration and a mathematical model of link attenuation is obtained,The relationship between the property of the charged particle and the quantum entanglement is proposed;according to the depolarized channel,the quantitative relationship between the radius of the dust particles,the particle concentration,the channel capacity and the quantum bit error rate is given.Thirdly,starting from the super dense coding transmission of quantum entangled states,a quantum super dense coding communication protocol based on four photon entangled states is proposed.Through this protocol,the entanglement channel can be established and the quantum information can be transmitted.Then the damage model of the quantum information transmission between the satellite and ground is explored,and the relationship between the transmission distance and the transmission damage rate is obtained.Next,a quantum repair strategy based on stratospheric quantum communication is proposed.The experiment shows that the repair strategy can reduce the loss of information transmission and increase the transmission distance of the quantum signal. |
PDF Full Text Request