Applications Of Photon Statistics For Quantum Key Distribution

Encrypt and decrypt have become a pair of immutable topics since the foundation of Cryptography. Cryptography plays an important role not only in the areas of military affairs and national defense, but also in the areas of economy and daily correspondence. In classical cryptography, keys must be bind to classical physical properties. These properties can be easily measured by anyone. So, eavesdropper can obtain keys without being discovered, no matter how the keys are distributed. There exists potential trouble with keys, which is the soul of classical cryptography. Quantum cryptography, the combination of cryptography and quantum mechanics, can perfectly settle the problem of key distribution, which cannot be settled by classical cryptography by using mathematic method. Thus, quantum key distribution (QKD) has become one of ten inventions that can change the world for its absorbing potential applications.One important presupposition of QKD is encoding one bit message on only one photon. The quality of single photon source is crucial to the safety of QKD. Although weak laser pulses are widely used in QKD experiments, they will decelerate the transmission speed for their excessive empty pulses and increase the error rate for their excessive multi-photon pulses. Therefore, theoretically and experimentally researching on single photon source becomes a crucial task for the further development of QKD.The main contents of this thesis are free-space QKD and the applications of photon statistics for QKD. QKD experiment has performed...