Theoretical Study Of Decoy State Quantum Key Distribution

Quantum cryptography or quantum key distribution (QKD) applies fundamental laws of quantum physics to guarantee secure communication, so security is a key point to quantum cryptography research. Many security analyses are based on the assumption that QKD system components are idealized. In practice, inevitable device imperfections may compromise security unless these imperfections are well investigated.The main purpose of this thesis is to study the practical effective QKD, to realize high speed and long distance secure quantum communication, and explore the practical application of quantum information. Although we focus on quantum cryptography, its research result can be referenced by mixing of quantum theory and telecom technology in other quantum information area, such as quantum computing. First we present the foundational knowledge of quantum information and basic theory of QKD, then we introduce the ideal decoy state QKD methods, and analyze the security of decoy states QKD with finite resources.Finally since the single photon is easy to attenuate and be disturbed, we study the more practical weak coherent pulse (WCP) and heralded single photon source (HSPS) QKD. We compare the performance of QKD using these two kinds of photon sources and decoy state method, incorporating data-postprocessing methods including the Lutkenhaus scheme and Gottesman-Lo-Liitkenhaus-Preskill (GLLP) scheme. Simulation results indicate that QKD using HSPS can transmit longer distance than using WCP with lower overall quantum bit error rate (QBER) at the same transmission distance, while with relatively low key generation rate.