【作者】 邵军虎；

【导师】 肖连团； 贾锁堂；

【作者基本信息】 山西大学 ， 光学工程， 2005， 硕士

【摘要】 由量子力学所保障的量子信息科学的产生,无疑对现代的通信理论、信息加密等许多领域带来了巨大的影响。作为量子信息科学最具潜力应用之一的量子密码通信,以其在安全性上的绝对优势而被广为关注。其中空间量子密码通信以其特有的优越性,对于将来实现量子通信网络、全球的卫星通信等都具有深远的重要意义。 本论文的主要研究内容有: 1、建立了基于B92协议方案采用偏振编码的空间量子密钥分配实验系统。 发送端Alice采用随机脉冲序列对单光子光脉冲进行偏振态编码后发送到自由空间;接收端Bob随机选择检偏基对接收光子进行测量,再以同步方式对单光子计数器的输出信号进行窗口选取测量。同时对Alice和Bob如何采取数据筛选、数据纠错、保密加强等技术,最终获得安全密钥的全过程进行了研究。另外分析了Eve的各种可能窃听策略对系统安全性构成的威胁。 2、APD探测器的自发辐射特性的实验研究。 非理想的单光子探测器性能仍是困扰当今量子密码通信的技术挑战之一。我们对Si-APD探测器(HAMAMATSU,S3884)的自发辐射特性进行了实验研究,给出其自发辐射光子的计数统计特性,光谱范围,峰值区间,以及光谱分布特性等。研究结果表明其暂态特性曲线为指数衰减曲线,工作在不同反向工作电压下的APD的光子辐射统计特性相似,其分布与热光场的Super-Poisson分布更为接近。其光谱特性的峰值响应波长在737nm和944nm处,波长范围在500nm～1100nm的宽带范围。 3、同步触发单光子探测系统的研究。 为了减小探测器暗计数和信道中背景噪声等因素对测量结果的影响,本文基于空间量子密钥分配的实验,提出了一个单光子检测系统的方案:在探测端采用外部电路对SPCM的测量计数值进行窗口更多还原

【Abstract】 This paper reviews some aspects of the development and application of quantum information and quantum cryptography, which is going to play an important role in the field of cryptography and the future worldwide quantum communication net.We make a Free-Space Quantum Cryptography system coding with single photon polarization states. Alice sends the single photon pulses with synchronizing light pulses, the receiver, Bob, detects the photons by our detection system with SPCM using the synchronizing electronic pulses to trigger. Then Alice and Bob get the sifted cryptographic keys by reconciling their keys through publicly discussion. After Error Correction and Privacy Amplification, the final secure quantum keys are acquired. The article also gives the analysis of existed eavesdropping strategies.Avalanche Photo-Diode has been widely used in the field of weak light detection, single photon detection and many kinds of photo-count detection. Nevertheless, the non-ideal characters of Single-Photon-Detection-Module give a challenge to Quantum Cryptography. Firstly, we measured the photo-statistic characteristic of the photon emission of silicon APD under the breakdown condition, studied experimentally its temporal character and fluorescence spectrum. Temporal decay process of photons emitting from avalanche photodiodes is demonstrated and it is found that there is a higher probability of photons emission after steep rise edge of the reverse voltage. To a Si avalanche photo-diode (HAMAMATSU, S3884), the photons emission have a broad spectral distribution from 500nm to 1100nm with two peaks at 750 nm and 994 nm, separately. We also find that the photons emission show super-Poissonian distribution. The current of the APD is the most important determinant of the photons emission. In order to reduce the background noise and dark counts in Bob’s detection, we present a更多还原