共查询到19条相似文献,搜索用时 125 毫秒
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单光子双比特量子密钥分发量子误码分析 总被引:3,自引:3,他引:0
对基于偏振-相位混合调制的单光子双比特方案进行了分析和改进。建立了偏振态输入输出模型,从理论分析了光纤Mach-Zehnder(M-Z)干涉环对偏振态的影响,仿真分析了偏振基矢与快慢轴对准误差以及快慢轴相位差引入的偏振编码量子误码率(BER),进而推导出了偏振-相位混合调制的光子偏振态保持条件。偏振编码的量子误码率受到M-Z干涉仪的影响非常大。理论分析表明,偏振态的抖动不仅来源于光纤的折射率,还受到偏振态未对准光纤快慢轴的影响。给出了一些重要的偏振态保持条件。仿真表明当ρ和θ小于0.2rad,偏振态量子误码率小于0.015,当ρ和θ小于0.4rad时,偏振态量子误码率小于0.06。这对于单光子双比特的量子密钥系统的误码率(<11%)要求来说,2%~5%的误码率是能够接受的。 相似文献
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宽角度位相调控反射镜是下一代中高轨量子通信系统中的核心元件,用于宽角度范围内信号光的高效传递与偏振态的精确调控。基于等效多层膜理论,采用介质反射膜堆加非规整位相调控膜的膜系结构,设计了一种宽角度位相调控反射镜。选择Nb2O5和SiO2分别作为高、低折射率薄膜材料,通过误差分析,优化沉积工艺,采用电子束蒸发结合离子辅助沉积的方式,在德国莱宝Lab900-plus设备上制备出该薄膜元件。研制结果表明,反射镜在780 nm处、45°±7.5°入射范围内,其反射率大于99.3%,位相差控制在3°以内,满足量子通信系统的反射率及位相差控制要求,且通过相关环境模拟实验,满足可靠性要求,为该类偏振调控薄膜元件在下一代中高轨量子卫星中的工程应用打下了坚实的基础。 相似文献
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由偏振分光棱镜、向列相液晶层、金属反射镜组成的LCoS投影微显示器件可以通过向列相液晶层的旋光效应、双折射效应而实现对入射偏振光的强度调制。为了提高光利用率,文章用Muller矩阵推导出了线偏振光经过扭曲向列相液晶层之后转变为偏振态不同的线偏振光或者圆偏振光的条件,设计了偏振转换效率为100%的常黑或常白LCoS显示模式,有效提高了光利用效率。 相似文献
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罗爱平 《激光与光电子学进展》2002,39(5):36-41
1 引 言全方向介质反射镜(也称作一维光子带隙晶体)[1,2]对从任意角度入射和任意偏振态的光都呈现100%的反射[3,4]。与金属反射镜(吸收一小部分入射光功率)不同,介质反射镜是无损耗的。这些特性使得全方向介质反射镜在某些领域具有潜在的应用前景,比如,一束不知道或不能预测偏振态的光可以从任何方向到达反射镜,而在反射镜上光的损耗不管多小都是不能容忍的。一个好的例子是光波导界面。因为当一束光通过时,从界面上发生无数的反射,即使在每个接触面微小的损耗都能很快地衰减光束的能量。一个典型的全方向反射镜由许多双… 相似文献
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本文提出了一种基于新型非周期高对比度亚波长 光栅(High Contrast Subwavelength Grating,HCSG)的谐振腔 增强型(Resonant Cavity Enhanced,RCE)光电探测器(Photodetector,PD),该器件是由顶 部光栅型上反射镜、PIN光探 测结构和分布式布拉格下反射镜(Distributed Bragg Reflectors,DBR)组成。新型非周期HC SG上反射镜是由局部湿法 氧化后形成的Al2O3间隔层和非周期GaAs光栅组成,实现了850 n m波段TM模式偏振光的高反射会聚特性,反射 率达到了86.5%且在1.5 μm焦距处实现了光束 会聚。下反射镜是由周期GaAs光栅和GaAs/Al0.9Ga0.1As DBR组成, 周期GaAs光栅对入射光有偏振选择特性,对TM模式的偏振光透射率为96.1%,而对TE模式的偏振光透射率仅有 3.7%。该器件利用了传输矩阵理论方法仿真模拟了其量子效率,量子 效率达到了71.8%,半高全宽接近于0.1 nm。 有效的解决了光电探测器的高量子效率和高响应带宽相互制约的问题,为下一代光通信系统 的发展提供了良好的基础。 相似文献
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In polarization-encoded free-space quantum communications, a transmitter on a satellite and a receiver in a ground station each have a respective polarization zero direction, by which they encode and decode every polarization quantum bit required for a quantum communication protocol. In order to complete the protocol, the ground-based receiver needs to track and compensate for the polarization zero direction of the satellite-based transmitter. Expressions satisfied by amplitudes of the s-polarization component and the p-polarization component are derived based on a two-mirror model, and a condition satisfied by the reflection coefficients of the two mirrors is given. A polarization tracking principle is analyzed for satellite-to-ground quantum communications, and quantum key encoding and decoding principles based on polarization tracking are given. A half-wave-plate-based dynamic polarization-basis compensation scheme is proposed in this paper, and this scheme is proved to be suitable for satellite-to-ground and intersatellite quantum communications. 相似文献
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大气传播特性对量子密钥分发性能的影响研究 总被引:1,自引:0,他引:1
根据电磁波传播与散射理论,考虑衰减和去极化效应等因素,建立了地空极化编码单光子源的传播模型,研究了空气衰减和天顶角与密钥生成速率间的关系,并建立了交叉极化分辨率和系统误码间的关系式;分析并仿真了大气环境对量子密钥分发的影响;结果表明:大气衰减对量子密钥分发系统每秒密钥生成数的影响较大;降雨条件下引起的去极化效应则会造成量子误码率增加. 相似文献
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Decision errors caused by quantum noise in an optical signal system have been experimentally detected. Such an experiment is necessary in order to facilitate the development of a future advanced zero error optical communication system. The apparatus consisted of two low dark-count photoelectron multiplying tube detectors which were used to detect two separate polarization components (X, Y) of manually controlled static binary polarization shift keying (PoISK) signals. With this system, events of the output state (0, 0) (the error events caused by quantum noise) were observed. Undesired error events for zero-error communication were also observed. Such events are caused by external noise such as polarization beam splitter leaks or dark-count (current) noise. However, the number of these error events was reduced by the suppression of polarization beam splitter leak noise 相似文献
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可光纤集成的相干态量子身份认证系统 总被引:1,自引:0,他引:1
报道了可光纤集成相干态量子身份认证实验系统。该系统采用偏振相干态的斯托克斯矢量作为量子信号载体,采用动态偏振控制器作为信号调制器,利用固有的相干态量子噪声保证系统的安全性。自行设计了脉冲激光驱动电路、微弱窄脉冲激光探测电路、信号同步模块,采用Socket网络通信程序在TCP/IP局域网中实现了量子保密通信所需要的经典通信。该相干态量子身份认证系统采用的运行密钥为12位,每个光脉冲包含40000个光子,传输速率达到8kbit/s,合法用户间误码率(BER)小于10-4。每传输一个比特信息,攻击者所能窃取的信息量I(Alice,Eve)<10-14bit。 相似文献
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The drive current of a directly modulated semiconductor laser for optical parallel data communication was investigated by taking into account both the threshold current and the differential quantum efficiency which are defined from the cavity length and the mirror reflectivities. Then the drive current required for an error free data communication (bit error rate: BER<10-9) with the bit rate of 1 Gb/s was shown as a function of the threshold current with parameters of the cavity length and the mirror reflectivities. It was found that the laser cavity design which yields the minimum drive current is almost the same condition to achieve the minimum threshold current operation when the total system loss is low (<10 dB), whereas the cavity design for higher differential quantum efficiency is required when the total system loss is much higher. When the cavity length is 100 μm and the rear mirror reflectivity Rr is 0.99 for an example, the front mirror reflectivity Rf which gives the minimum drive current was obtained to be 0.94, 0.91, and 0.8 for the total system loss of 6, 10, and 20 dB, respectively 相似文献
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Coherent lightwave communications systems are approaching a limit where the error rates and channel capacities are limited by the quantum properties of light. This is often referred to as the shot-noise limit. If ideal laser light is used in the system, there is no way to avoid this limit. However, new states of the light field called squeezed states have recently been developed that allow an improvement in error rates below the shot-noise limit. Squeezed light concepts and recent experiments are reviewed with emphasis on aspects important to coherent communications. It is shown that channel capacity can be improved using squeezed light by only a factor of two. Larger improvements are in principle possible for error rates, e.g. a factor of three reduction in the number of required photons per bit for a 10-9 bit error rate. An example of a recent high-performance system is described where optical losses and electronic noise reduce the improvement expected using squeezed light to the 10-20% level. It is concluded that squeezed light only offers significant improvement in bit error rates for very-high-efficiency systems 相似文献