Simulation Of Quantum Key Distribution And Research On Decoy State

Quantum key distribution (QKD) is the combination of quantum mechanics and quantum cryptography, whose unconditionally secure private communication is based on Heisenberg's uncertainty principle of quantum mechanics and no-cloning theorem. However, the quantum key rate and the maximum security distance are confined by the imperfect devices in practice (such as the imperfect single photon sources, the channel transmistance loss in optical fiber, the dark count of detection and so on).Classical computer simulation is an important method to study the QKD communication. It is much closer to experiment than theory. What's more, It doesn't need high funding and complex technology like experiments. In this paper, the simulation of quantum cryptography communication and the decoy state based on coherent source which can realize the unconditionally secure OKD based on the existing technology are studied. This research is to improve the QKD for practical use. The main contents are:1) The concepts of BB84 protocol, B92 protocol, amplitude damping channel and depolarizing channel are introduced. Then, a new simulation method is proposed and a Matlab software is used to simulate BB84 protocol in amplitude damping channel, BB84 protocol with angle deviating in amplitude damping channel, and B92 protocol in depolarizing channel to get the quantum key rate on classical computer. Furthermore, the BB84 protocol in amplitude damping channel is simulated via two different data reconciliation methods and their comparison is provided. The simulation result of the bit rate from the BB84 protocol in amplitude damping channel fully satisfy the private channel capacity which is given by Giovannetti and Rosario Fazio. The channel capacity of B92 protocol in depolarizing channel has not been determined theoretically yet.2) I compare two different data reconciliations, namely binary reconciliation and cascade reconciliation, by the simulation results of BB84 protocol in amplitude damping channel. The simulation results show that when the amplitude damping parameterγ<0.15, the cascade reconciliation is better than binary reconciliation, when the amplitude damping parameter0.15<γ<0.5, the binary reconciliation is better than cascade reconciliation. They both have their own advantages and disadvantages.3) I simulate and calculate a decoy state method with coherent state on the classical computer with Matlab software to verify that the decoy state method can fight effectively against the Photon Number Splitting Attack.Finally, conclusions and future work on QKD communication simulation are introduced.