Theoretical Study On Reference Frame Independent Quantum Key Distribution With Source Flaws

With the rapid development of information society,the role of quantum cryptography in information security began to receive widespread attention.Quantum key distribution(QKD),as the core of quantum cryptography,allows two remote parties to share an unconditionally secure key to ensure the secure transmission of information.The unconditional security of QKD is based on the basic principles of quantum mechanics and has been proven in theory.However,the imperfection of the actual devices are not considered,which may compromise the security of practical QKD systems.This thesis mainly focus on the theoretical study of reference frame independent quantum key distribution with source flaws,which can better promote the protocol into practical use.The main covered parts are as follows.We first consider the model of reference frame independent quantum key distribution(RFI QKD)with source flaws.In RFI-QKD protocol,three mutually unbiased bases(Z,X,and Y bases)are used to encode the information.Generally only the Z basis is used to generate the final key and are needed to be aligned,while the other bases are not required to be exactly matched.Based on the loss-tolerant technique,instead of using six encoding states in the standard RFI QKD,only four encoding states are required in our analysis.We also have considered whether the RFI-QKD protocol is still reference independent when there are source flaws.Besides,we simulated the key generation rate of RFI QKD with source flaws.The traditionally GLLP method pessimistically assumes that Eve can enhance the flaws in the single-photon part by exploiting the losses of that part,which leads to a severe degradation of the system performance.Instead of using the GLLP method to estimate the phase error rate,we used loss-tolerate method,which can give better description of the phase error rate as well as the key generation rate.In addition,RFI QKD with four perfect encoding states can supply a performance comparable to the three-state protocol and BB84 protocol.