Preparation And Transmission Of High Fidelity Quantum States In Quantum Physical Layer Secure Communication

At present the classical cryptographic communication mode with public key cryptosystem as the mainstream is mainly based on computational complexity,but with the development of supercomputers,especially quantum computers,this traditional communication mode based on computational complexity is no longer safe.Quantum secure communication is a subject that combines quantum mechanics with classical communication,which changes the traditional communication mode and makes both parties have higher communication security.Now it is widely used in national defense,military affairs,finance,politics,economy and trade and other important fields,plays an indispensable role and has broad application prospects.Since the introduction of quantum secure communication,many protocols and schemes have been proposed and their security has been proved.In recent years,the research of quantum secure communication is more practical.This paper aims at the practical research of quantum secure communication,takes the system of quantum physical layer secure communication as the overall research framework,and puts forward some solutions to solve some key technical problems encountered in quantum physical layer secure communication and promote the practical application of quantum physical layer secure communication.The main research work of this paper is as follows:1.Research on polarization control integration of quantum physical layer secure communication.In the quantum secure communication based on polarization coding,the polarization state can’t remain stable for a long time due to the external temperature,stress and the irregularity of its own optical fiber,which affects the stability of the system and increases the bit error rate of the system.In order to solve the problem of polarization state preparation and stability in quantum secure communication,part of the work in this paper takes FPGA as the central controller,and considering the integration of polarization control,an integrated polarization control scheme is proposed,which integrates quantum state preparation,strong light polarization control and single photon polarization control.The experimental results show that the polarization fidelity of strong light is(99.11 ±0.44)% and that of single photon is(97.93±0.96)%.2.Practical research on optical fiber transmission of secure communication image in quantum physical layer.In order to promote the practicality of quantum secure communication,the ultimate goal of secure communication system is to realize the transmission of text files such as voice or image information,and the collection and reception of information is a key part of secure communication.In order to solve the problem of information collection and reception in quantum physical layer secure communication,this paper takes FPGA as the central controller and computer as the data collection and reception equipment,designs the upper computer software and converts images into binary data.It is convenient for hardware devices to modulate the quantum state and transmit it through optical fiber,and finally realize the image recovery of the host computer at the receiving end,which provides effective help for the information acquisition and receiving system in the quantum physical layer secure communication and further promotes the practicality of the quantum physical layer secure communication.