星-地量子密钥分发链路持续时间分析与仿真

链路持续时间是影响卫星量子密钥分发量子比特率的重要参数.文章分析了影响星-地单光子和纠缠光子量子密钥分发链路持续时间的若干因素,并且进行了数值仿真研究.结果表明,随着轨道高度的增加或者地面最小通信仰角的减小,单光子和纠缠光子链路的持续时间有较大的改善;单光子链路时地面站同卫星星下点轨迹间的距离和纠缠光子链路时两地面站之间的距离也均是影响链路持续时间的重要参数;纠缠光子链路持续时间的影响因素较单光子链路更为复杂,其最终决定于卫星星下点轨迹同两地面站之间的位置关系.     

降雪干扰下基于演化博弈的低轨量子卫星多用户切换策略

低轨道量子卫星是构建全球天地一体化量子保密通信网的重要组成部分。单颗低轨量子卫星服务时间有限,为了保证卫星与地面用户之间的持续通信,地面终端需要及时切换至其他可供服务的卫星。为了解决降雪环境干扰下地面多用户量子卫星切换场景下的阈值判决问题,分析了大气雪环境对量子星地链路的衰减影响,提出了一种基于演化博弈的多属性量子卫星切换策略。根据用户的带宽、卫星剩余服务时间及链路衰减三个属性定义效用函数,根据星间传输时延、信道纠缠度定义开销函数,最终得到用户的收益函数,建立演化博弈切换模型。仿真结果表明,该策略具有稳定性和公平性,能够有效均衡卫星的负载,且与基于最低链路衰减和最优纠缠度的单属性切换策略相比,切换成功率分别提升了1.2%和1.5%,这对未来降雪干扰环境下低轨量子卫星网络的多用户动态切换有一定的参考意义。     

一种新型准静态拓扑LEO/MEO卫星光网络设计

设计了一种新型的LEO/MEO全球覆盖双层卫星光网络,该结构具有稳定的MESH型连接关系,不仅满足卫星光通信捕获追踪和瞄准ATP(acquisition tracking and pointing)要求,还能简化星载处理和交换,降低路由开销。推导了同层和异层间星间链路空间位置表达式。数值仿真结果表明该网络相邻卫星间距离、方位角和俯仰角变化范围小,非常适合卫星激光链路,可作为构建未来卫星激光网络的参考。     

基于OPNET的星地光网络性能测试仿真平台研究

为了测试星地光网络的性能,设计了一种基于OPNET的星地光网络性能测试仿真平台。介绍了平台的总体技术架构,探讨了星间链路建立的条件。采用最大接入仰角与最长服务时间加权的方式,完成星地链路的卫星接入服务;按照切换呼叫优先的策略完成业务传输中的卫星切换服务,确保星地链路不间断的通信能力。根据最小链路代价和首次命中原则,实现星地光网络的路由与波长的动态分配。最后,利用平台的OPNET软件测试了三种星座下的星地光网络性能,测试结果表明：在LEO、MEO和GEO星座下,星地光网络的网络阻塞率分别为10%、40%和54%,平均网络时延分别为0.1s、0.07s和0.054s。测试结果对星地光网络的工程应用具有一定的指导意义。     

光通信 激光通信

TN927.132006054576恒星背景噪声对星间激光链路跟瞄系统影响的仿真分析=Influences of stellar background noise on tracking andpointing subsystemof intersatellite optical communications[刊,中]/韩琦琦(哈尔滨工业大学可调谐激光技术国家级重点实验室,光电子技术研究所.黑龙江,哈尔滨(150001)),马晶…//光学技术.—2006,32(3).—444-448根据卫星轨道理论及恒星数据库建立仿真实验系统,对低轨卫星与中继卫星间(LEO-GEO)、中继卫星间(GEO-GEO)、低轨卫星间(LEO-LEO)三种典型的星间激光链路—84—进行了仿真研究,深入分析了恒…     

激光星间链路终端技术发展与展望北大核心CSCD

激光星间链路主要用于卫星之间高速数传,是构建天基信息网络的关键技术。目前国外通信、遥感、导航和中继等卫星系统都已计划部署激光通信终端,激光星间链路技术已从在轨演示验证向大规模组网应用阶段发展。简要梳理了国际上现有组网卫星系统的激光星间链路终端技术发展情况,对激光星间链路的技术体制和终端分类进行了总结;侧重分析了我国激光星间链路终端技术发展现状及大规模应用面临的主要问题,针对重难点技术的解决途径进行了思考;对激光星间链路终端未来的发展趋势做了展望,尤其是轻小型化设计与实现、宽带化、一对多光学天线和网络化等技术发展趋势进行了分析。     

基于纠缠态的量子通信网络的量子信道建立速率模型

针对基于纠缠态的量子通信网络, 提出了网络模型. 基于网络模型, 首先分析了基础链路的量子信道建立速率. 然后根据基础链路的量子信道建立速率, 针对不同的量子信道建立方法, 对中继长链路上的量子信道建立速率进行分析, 得到在逐点方法和分段方法下所对应的量子信道建立速率. 最后, 利用逾渗模型, 对大规模纠缠态量子通信网络中任意两点间的量子信道建立速率进行分析, 推导出n个节点量子通信网络中, 量子信道建立速率为Ω (1/n).     

基于TDMA的星间链路时隙分配设计与仿真评估

基于TDMA的星间链路体制组网灵活,传输效率高,已成为今后星间链路的一种发展趋势。对于TDMA的星座网络而言,其时隙分配是影响业务时延的重要因素,本文就一种双层混合型星座提出了一种时隙分配方案,并对星座网络的传输进行了仿真,分别从广播和单播两种业务的角度针对星间链路传输性能的时延指标进行了评估分析。     

星间微波光子链路调制方式的优化

针对外调制星间微波光子链路输出信噪比优化问题,建立了基于双电极马赫 曾德尔调制器的强度调制直接探测星间微波光子链路模型,通过优化调制器调制方式来提高链路性能。用数值模拟方法得到了单边带、双边带和推挽式3种调制方式下链路输出信噪比,利用曲面投影法求得了最优调制方式时一定信噪比要求下发射端所需最小光放大器增益和对应的调制器直流偏置相位。结果表明:相同输入射频信号功率和发射光功率情况下,双边带调制输出信噪比比单边带调制高3 dB,低直流偏置相位推挽调制可以进一步优化输出信噪比。输入射频信号功率为-20 dBm,输出信噪比为17.3 dB时,所需最小光放大器增益为43.9 dB,对应的直流偏置相位为0.87。     

光通信 激光通信

TN929．1 2005010638 星间激光通信系统=Laser intersatellite communication [刊,中]／吴春水(中国电子科技集成公司第27研究所.河南,郑州(450005)∥电光系统．-2004(3)．-10-14 阐述了星间激光通信的概念及特点,介绍了激光通信的发展及研究现状,并论述了星间激光通信的技术体系及关键技术。论述了我国在星间激光通信研究方面取得的成果,提出了我国在发展星间激光通信领域的建议。图3 参8(于晓光)     

Analysis of inter-satellite free-space optical link performance considering different system parameters

The welcome and adaptation of optical wireless technology by the modern era has brought forward the concept of an inter-satellite free-space optical communication system. In the present work, I study the combined effect of selection of different operating wavelengths and detector types along with the pointing errors at the transmitter and receiver side on the performance of an inter-satellite free-space optical link. The link performance has been optimized by measuring and analyzing the bit error rate and quality-factor of received signal under different scenarios. Performance of the inter-satellite link has also been investigated considering different modulation formats and data rates for LEO and MEO distances.     

Continuous-Variable Quantum Secret Sharing Based on Thermal Terahertz Sources in Inter-Satellite Wireless Links

We propose a continuous-variable quantum secret sharing (CVQSS) scheme based on thermal terahertz (THz) sources in inter-satellite wireless links (THz-CVQSS). In this scheme, firstly, each player locally preforms Gaussian modulation to prepare a thermal THz state, and then couples it into a circulating spatiotemporal mode using a highly asymmetric beam splitter. At the end, the dealer measures the quadrature components of the received spatiotemporal mode through performing the heterodyne detection to share secure keys with all the players of a group. This design enables that the key can be recovered only by the whole group players’ knowledge in cooperation and neither a single player nor any subset of the players in the group can recover the key correctly. We analyze both the security and the performance of THz-CVQSS in inter-satellite links. Results show that a long-distance inter-satellite THz-CVQSS scheme with multiple players is feasible. This work will provide an effective way for building an inter-satellite quantum communication network.     

Geometrical optics in Fresnel quantum holography

The geometrical optics in Fresnel quantum holography for quantum entangled two-photon source and classical thermal light source based on the second-order correlation measurement has been discussed. We theoretically prove that the Fresnel quantum hologram of the detected object can be obtained through second-order correlation measurement and the optical reconstruction process can be accomplished by making use of a point light source.     

Kinetics of dense matter: Correlations and memory

A link between correlation contributions to kinetic equations for dense quantum systems and the energy conservation is considered. In order that the energy be conserved by an approximate collision integral, the one-particle density matrix and the mean interaction energy are treated as independent state parameters. It is shown how the density operator method can be used to derive non-Markovian kinetic equations including the correlation effect associated with the energy conservation. A quantum generalization of the Enskog theory is discussed. The text was submitted by the author in English.     

Non-classical correlation of the two emission fields by a four-level atomic ensemble

The normalized second-order correlation of the emission fields from a driven four-level atomic ensemble is investigated theoretically by using the state vector method. The violation of Cauchy-Schwarz inequality, which indicates the establishment of non-classical correlation between two emission fields, has been found. The effects of various decays and time delay on the correlation are discussed in detail, which are helpful in finding the ways to obtain high non-classical correlation. This technique for the generation of non-classical light is operable based on the current experimental technology and will lead to some potential applications in quantum information science.     

基于分组交换的量子通信网络传输协议及性能分析

量子纠缠交换能够建立可靠的量子远程传输信道, 实现量子态的远程传输. 然而, 基于纠缠交换的量子信道要求网络高度稳定, 否则会浪费大量纠缠资源. 为节省纠缠资源, 本文根据隐形传态理论, 提出了一种基于分组交换的量子通信网络传输协议, 建立了发送量子态所需的纠缠数目与所经过的路由器数、链路错误率的定量关系, 并与纠缠交换传输协议进行了比较. 仿真结果表明, 在链路错误率为0.1% 时, 分组传输协议所使用的纠缠数目少于纠缠交换的数目, 另外, 随着错误率的升高, 分组传输协议所需的纠缠数比纠缠交换协议明显减少. 由此可见, 基于分组交换的量子通信网络传输协议在网络不稳定时, 能够节省大量纠缠资源, 适用于链路不稳定的量子通信网络.     

Error corrections of quantum key distribution of the quantum codes via optical wireless link

Quantum key generated by using a fiber optic Mach Zehnder interferometer incorporating a fiber optic ring resonator is proposed. The generated quantum key is distributed via an optical wireless link system, which is available for the free space link. The random quantum bits can be formed and used as the secret codes in quantum communication system. By adding an ancillary photon after the signal photon within the correlation time of the fiber noise and by performing quantum parity checking, the high fidelity to the noiseless quantum in free space is achieved by the technique known as the quantum error correction.     

Active measuring method for investigating the irradiation effect on the gain characteristics of an erbium-doped fiber amplifier in inter-satellite optical communication

An active measuring method is proposed for the first time to study the irradiation effect on the gain characteristics of an erbium-doped fiber amplifier (EDFA) for inter-satellite optical communication, which is feasible from the engineering viewpoint. The measuring method based on the irradiation model can predict the irradiation effect on the gain characteristics just by measuring the variation of the EDFA signal output power at one irradiation dose rate in the irradiation experiment. Therefore, one can avoid removing the erbium-doped fiber (EDF) from the EDFA, which is needed in the previously tested passive measuring method. These experimental measurements meet completely the requirements of the technical specifications for inter-satellite optical communication. Finally, an irradiation experiment has also been carried out to evaluate the new method by a simple test procedure.     

以交叉分子束及时间切片离子速度成像法研究产物成对相关讯息

研发了一种新颖的实验方法 ,用以在交叉分子束条件下测量双分子反应产物的成对相关 (paircorrela tion)讯息 .作为尝试 ,首先选取了F +CD4/CHD3 /CH4反应体系 .结合时间切片离子速度成像与交叉分子束技术 ,可直接测得产物态分辨且成对相关的角分布 .已研究了产物成对相关的几个方面 ,阐释了碰撞能效应 .测量表明 ,产物角分布对HF/DF产物振动态有极强的相关性 ,同时对甲基产物的振动态也有不可忽视的相关性 .在低碰撞能时 ,在F +CH4多原子反应中 ,首度发现了反应动态共振的证据 .