Research On Security And Decoherence Suppression Of Quantum Key Distribution System

With the rapid development of quantum information technology, more and more mature quantum key distribution technology is expected to provide secure key distribution mechanism for the actual information systems. The unique advantage of quantum key distribution technology lies in its unconditional security, whose theoretical security has been proven. However, in practical quantum key distribution system, the device’s imperfection makes opportunities for eavesdropper which has negative impact on key rate and quantum bit error rate. Therefore, the research on the security of actual quantum key distribution system is of great importance to improve key rate and quantum bit error and the development of quantum communication technology.Although quantum information has unparalleled advantages over classical information, we meet with a serious obstacle named as de-coherence due to the interaction between the system and the environment. Decoherence has negative influence on the efficiency of processing quantum information and key rate and quantum bit error. Given the prevalence and severity of the effects of de-coherence, how to suppress de-coherence has become a very essential and important research topic.This paper is focused on security and decoherence suppression of quantum key distribution system. The work of this paper is as follows:Firstly, quantum cryptography relevant background knowledge is introduced, including basic knowledge of quantum mechanics, two typical quantum key distribution protocols and two important technologies such as preparation of single photon signal and detection of single photon.Several typical side-channel attacks such as PNS attack, phase remapping attack and blinding attack and their own anti-attack measures are also discussed in detail. Loopholes in QKD platform are analyzed in detail and counter-measures are given.Weak measurement-reversal is introduced in detail and it is applied to suppress amplitude damping channel noise. By derivation and simulation using MATLAB, it turns out that in ideal case quantum state is close to initial state and decoherence is suppressed totally.Finally, weak measurement-reversal is applied to suppress dephase and depolarization channel noise. Detailed derivation proves that the impacts on quantum fidelity is closely related to the initial state, strength of weak measurement and reversal measurement and degree of decoherence. The result obtained by MATLAB identifies with the theory.The following study is still needed on the basis of this paper:Look for loopholes in QKD platform, solve them and improve platform to increase key rate and reduce the quantum bit error rate.The influence on key rate and quantum bit error of quantum key distribution system caused by weak measurement-reversal when suppressing decoherence needs to be further discussed.