Exponential networked synchronization of master-slave chaotic systems with time-varying communication topologies

The networked synchronization problem of a class of master-slave chaotic systems with time-varying communication topologies is investigated in this paper. Based on algebraic graph theory and matrix theory, a simple linear state feedback controller is designed to synchronize the master chaotic system and the slave chaotic systems with a time- varying communication topology connection. The exponential stability of the closed-loop networked synchronization error system is guaranteed by applying Lyapunov stability theory. The derived novel criteria are in the form of linear matrix inequalities (LMIs), which are easy to examine and tremendously reduce the computation burden from the feedback matrices. This paper provides an alternative networked secure communication scheme which can be extended conveniently. An illustrative example is given to demonstrate the effectiveness of the proposed networked synchronization method.     

自由大气紫外光学通信的研究

本文对紫外日盲区光谱在近距离、保密通信中的应用进行了探讨 ,并建立了紫外光学通信原理实验系统。所描述的系统是以日盲区紫外光作为信息载体的 ,用被调制的低压汞蒸汽紫外放电灯作为发射器件 ,以日盲型滤光片和光电倍增管或日盲型紫外光电倍增管作为接收器件 ,以达到在任何时间和在任何气候下完成窄频带模拟或低速数字信号的传输。由于近地表大气臭氧层的吸收 ,所以传输距离被限制在一个较小的范围内 ,构成了短距离的、秘密的、安全的和抗干扰的通信系统 ,并且不需要传统意义上的天线。由于地球大气上层臭氧的吸收作用 ,阳光中的日盲区 (2 0 0～ 2 80 nm)辐射几乎无法到达地球表面 ,因此 ,采用这个波段的光学通信系统几乎不会受到太阳光的干扰。典型的大气臭氧浓度高度分布大约在距地表 2 5 km处达到最高值 ,在海平面处有一个较低的值。相对较低的浓度值来说 ,虽然紫外辐射传输有限 ,但是具有足够远的距离 ,同时可达到安全、秘密和抗干扰的目的     

980nm单模运转未镀增透膜光纤光栅激光器

提出了一种工艺简单的980nm未镀增透膜的光纤光栅外腔半导体激光器。首先从理论上分析了边模抑制比(SMSR)与激光二极管前表面反射率R2、外腔长Lext和激光二极管一光纤耦合效率之间的关系,得出边模抑制比随R2和Lext的增大而减小,而随着激光二极管一光纤的耦合效率的提高而增大。从计算结果中还可以看出,即使半导体激光器不镀增透膜(R2=0．3时)。在其它参量合适的情况下,边模抑制比仍可大于40dB。然后,对其进行实验验证。在半导体激光器未镀模的情况下,选择光纤光栅发射率为0．5,外腔长为12．5cm,输人电流为28．8mA(约为阈值电流的2．4倍)时,通过仔细调节恒温、恒流电路,实现了边模抑制比高于40dB的稳定的单纵模输出,外腔激光器的线宽优于1．6MHz。     

Sender-controlled measurement-device-independent multiparty quantum communication

Multiparty quantum communication is an important branch of quantum networks. It enables private information transmission with information-theoretic security among legitimate parties. We propose a sender-controlled measurement-device-independent multiparty quantum communication protocol. The sender Alice divides a private message into several parts and delivers them to different receivers for secret sharing with imperfect measurement devices and untrusted ancillary nodes. Furthermore, Alice acts as an active controller and checks the security of quantum channels and the reliability of each receiver before she encodes her private message for secret sharing, which makes the protocol convenient for multiparity quantum communication.     

基于组态软件和多串口通讯的真空检漏监测系统设计与开发

许 婕,蔡立君,卢 勇,罗 山,张 龙,田培红     

极大加可约矩阵的谱与周期时间向量的关系

提出了极大加代数上可约矩阵特征值的缺失值及冗余值的概念,得到了相应的定理;对特征值与周期时间向量分量之间的关系作了深入的研究.     

Circular threshold quantum secret sharing

This paper proposes a circular threshold quantum secret sharing （TQSS） scheme with polarized single photons. A polarized single photon sequence runs circularly among any t or more of n parties and any t or more of n parties can reconstruct the secret key when they collaborate. It shows that entanglement is not necessary for quantum secret sharing. Moreover, the theoretic efficiency is improved to approach 100% as the single photons carrying the secret key are deterministically forwarded among any t or more of n parties, and each photon can carry one bit of information without quantum storage. This protocol is feasible with current technology.     

光纤弯曲损耗特性的理论与实验研究

为了减小在长距离光纤通信中存在的弯曲损耗和利用光纤激光器中的弯曲损耗获得单模输出，利用速度法解释了光纤弯曲损耗机制，采用Marcuse理论研究了弯曲损耗随弯曲半径、波长和纤芯半径变化的关系。通过计算机仿真和实验得出弯曲损耗随弯曲半径的减小而增大，随波长的增大而增大，随纤芯半径的增大而增大，高阶模式的损耗大于低阶模式。利用这一结论就可以通过控制弯曲半径在临界半径以内来减小通信中的弯曲损耗，通过增大模场半径来实现光纤激光器中的单模输出。     

大气激光通信链路的性能仿真

大气衰减和大气湍流严重影响着大气激光通信的链路质量。建立了大气信道的激光通信链路模型，研究了衰减信道和湍流信道中光链路的传输影响，对最大通信速率、链路功率余量和误码率进行了分析和计算。结果表明，大气湍流严重影响系统误码率，当大气闪烁指数斫是0．07时，可达到的最小误码率为10^-9。分析结果可为系统设计提供参考依据。     

Ion-trap quantum information processing:experimental status

Atomic ions trapped in ultra-high vacuum form an especially well-understood and useful physical system for quantum information processing. They provide excellent shielding of quantum information from environmental noise, while strong, well-controlled laser interactions readily provide quantum logic gates. A number of basic quantum information protocols have been demonstrated with trapped ions. Much current work aims at the construction of large-scale ion-trap quantum computers using complex microfabricated trap arrays. Several groups are also actively pursuing quantum interfacing of trapped ions with photons.