Population Diagnostics of a Hot NaBr Plasma by Detailed Simulation of Absorption Spectra

The experimental absorption spectra of a hot NaBr plasma are theoretically studied by using a detailed level accounting model. The sodium and bromine absorption spectra have been well reproduced respectively in the approach of local thermodynamic equilibrium, in which the populations between and within ions are obtained by solving the Saha-Boltzmann equation. The temperature of bromine however is found to be much lower than the one of sodium. Such discrepancy indicates that thermodynamic equilibrium is not reached between the sodium and bromine atoms during the measurement.     

Quantum Secret Sharing with Two-Particle Entangled States

We present a new protocol for the quantum secret sharing （QSS） task among multiparties with two-particle entangled states. In our scheme, the secret is split among a number of participatlng partners and the reconstruction requires collaboration of all the authorized partners. Instead of multiparticle Greenberger-Horne-Zeillnger states, only two-particle entangled states are employed in this scheme. By local operations and individual measurements on either of the two entangled particles, each authorized partner obtains a sequence of secret bits shared with other authorized partners. This protocol can be experimentally realized using only linear optical elements and simple entanglement source. It is scalable in practice.     

基于混沌序列的密钥生成新方法

设计了一种从混沌序列生成密钥的新方法.其基本原理是从混沌序列依次取若干数据构成实值序列,将其按非线性规则映射成二值序列,再用实值序列和任意指定序列分别置乱这个二值序列,被置乱后的二值序列即为所生成密钥.实验表明,在混沌密码体制研究中,这种密钥较一般序列密钥更具有独立性、均匀性和不可预测性.     

带常数边界的平衡更新风险模型的破产问题

本文讨论带常数边界的平衡更新风险模型的破产问题.利用Markov性质,给出惩罚函数满足的积分-微分方程,证明其惩罚函数可由更新风险模型的惩罚函数表示,并且给出一个具体的例子.     

凸模糊映射的共轭映射

本文在Goetschel和Voxman所建立的拓扑向量空间中引入了反模糊数的概念,并建立了反模糊数空间,讨论了有关的基本性质.在此基础上,引入了凸模糊映射的共轭映射的定义,并证明了凸模糊映射的共轭集合和共轭映射都是凸的.     

Polarization Encoded Quantum Key Distribution over Special Optical Fibres

Employing a polarization compensator, an optical fibre quantum key distribution （QKD） system based on polarization coding has been developed. To obtain the compensator setting parameters, the measurement of the laser pulse polarization is performed with one single photon detector. We obtain a sifted key bit rate of about 2kbits/s and a qubit error rate lower than 10% within 3.5h. It is shown that polarization coding can be used for QKD over optical fibres as well. At the same time, the system is simple, easy to operate, practical and user-friendly. It gains more advantages than other systems over optical fibres when used in local area quantum communications and where the functional agility is important.     

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介绍了一种广泛应用于离子刻蚀、预清洗和离子束辅助镀膜的阳极层离子源的工作原理,分析了磁场对其性能的影响。给出了线性阳极层离子源磁路的设计。采用ANSYS有限元分析软件对线性阳极层离子源的静态电磁场进行了模拟分析,并与实验结果进行了比较,结果令人满意。通过ANSYS编码对电磁场模拟,可为具体的阳极层离子源的改进设计提供指导。     

Xe原子吸附对GaAs(110)表面重构的影响

基于第一性原理的自洽场密度泛函理论(DFT)和广义梯度近似(GGA),利用缀加平面波加局域轨道(APW+lo)近似方法，建立了五层层晶超原胞模型，模拟了GaAs(110)表面结构和单个Xe原子在其表面的吸附.利用牛顿动力学方法，对GaAs(110)表面原子构形的弛豫和Xe原子在GaAs(110)表面的吸附进行了计算.从三种不同的初始构形出发，即Xe原子分别在Ga原子的顶位，As原子的顶位以及桥位，都发现Xe原子位于桥位时体系能量最低.由此，认为Xe原子在GaAs(110)表面的吸附位置在桥位，并且发现吸附Xe原子后GaAs(110)表面有趋向于理想表面的趋势，表面重构现象趋于消失，表面原子间键长有一定的恢复,这与理论预言相符合. 关键词： 密度泛函理论 表面结构 APW 表面原子吸附     

例说用坐标法解立体几何问题

《普通高中数学课程标准》将空间向量引入中学数学,并用它研究空间线、面的位置关系,计算空间角与距离,使几何问题代数化.与立体几何传统的解法相比较,向量法降低了对图形的处理技巧,也不需要很强的逻辑推理,为解决立体几何问题注入了新的活力.