【作者】 黄涛；

【导师】 贾锁堂； 肖连团；

【作者基本信息】 山西大学 ， 光学， 2006， 博士

【摘要】 自从人类有了保密通信以来，怎样在通信中保密以及如何破译敌方的密码就是一对永恒的话题。保密通信不仅在军事、国防等领域发挥独特作用，而且在当今的经济和日常通信等方面也日渐重要。在经典的方案中，不论建立密钥的过程多么保密，原则上窃听者总可以窃取到这个密钥，而通信双方对此毫无察觉。这是因为密钥的建立过程总要利用某种载体的某种物理性质，而经典物理学指出，人们完全可以测量该载体的这些属性而不对其产生任何影响。故经典密码术的核心部分一密钥存在不安全因素。量子力学和密码学的结合一量子密码术，成功地解决了传统密码学中仅依靠数学无法完成的密钥保密传递问题。量子密码术潜在的巨大应用前景引起了全世界人们的广泛关注，量子密码也被称为改变人类未来的十大发明之一。 量子密钥分发的一个重要前提条件就是使用单个光子携带信息，单光子源的质量是关系到整个通信过程安全性的重要因素。目前大多数量子密钥分发实验所用的光源都是经过强烈衰减的弱光脉冲，这种光源存在着许多的多光子和空脉冲事件，因此严重降低了密钥分发系统的传输效率，增大了误码率。所以当前在理论和实验上寻找单光子源已经成为推动量子密钥分发进一步发展的重要课题之一。 本论文主要就自由空间量子密钥分发以及光子统计在自由空间量子密钥分发中的应用进行了理论分析和实验研究。基于偏振编码的B92协议在自由空间中进行了量子密钥分发的实验演示，研究了用于单光子探测的雪崩光电二极管的暂态发光特性，并且提出了基于外部光电开关的更多还原

【Abstract】 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更多还原