Performance Study Of Practical Quantum Key Distribution System

Quantum Key Distribution(QKD)is a key distribution method based on the fundamental theorem of physics.It is a compound application combining quantum theory and information theory.And it is proved to be absolutely safe by the physics theorem.However,in practical applications,there are still some loopholes in current experimental devices,such as non-ideal single-photon sources,detectors with low detection efficiency,fluctuation of experimental system and so on.It will affect the final key generation rate and the maximum communication distance,and it even introduces security loophole in the system.In response to the photon number splitting attack of imperfect sources,decoy state method was proposed.Since then,it has been continuously developed and improved.In order to eliminate all the attack on the measurement side,the measurement device independent quantum key distribution(MDI-QKD)was proposed.MDI-QKD solves most of the loopholes in the system and becomes a highly secure quantum key distribution system that can be practically deployed.Based on this,our paper further discusses the performance of decoy state measurement-device-independent quantum key distribution system under practical source,analyses the influence of statistical fluctuation on system performance,and analyses the effect of parameter optimization on system performance improvement.In this thesis,we first introduce the research background and recent progress of quantum communication.Then we introduce the basic theory and common protocols of quantum key distribution.Then we introduce the theory and protocol of measurement-device-independent quantum key distribution in detail,and derive key rate equation using methods of different number of decoy state.When considering the fact of finite length of raw key,we introduce the standard error analysis method to analyze the impact of statistical fluctuations on key rate and parameter optimization.Then we simulated and compared the performance of measurement-device-independent quantum key distribution with different number of decoy states.The statistical fluctuation due to the finite length of data is considered to analyze the practical performance of decoy-state MDI-QKD based on the standard statistical analysis.In all simulation cases,the key rate is maximized by optimizing the intensities of the signals.The simulation results show that two-decoy-state method is a nearly optimal estimation in the asymptotic case.In the condition of considering statistical fluctuations,the finite length of raw key will slightly decrease the secret key rate.Our numerical simulation may provide valuable theoretical reference for the practical MDI-QKD experiments.