低强度飞秒激光激发下CdTe和CdTe/CdS核壳量子点的荧光上转换研究

利用400 nm和800 nm不同波长的低强度飞秒激光,对CdTe和CdTe/CdS核壳量子点溶胶进行激发,研究其稳态和时间分辨荧光性质.800 nm飞秒激光激发下,CdTe和CdTe/CdS核壳量子点产生上转换发光现象,上转换荧光峰与400 nm激发下的荧光峰相比蓝移最多达15 nm,而且蓝移值与荧光量子产率有关.变功率激发确认激发光功率与上转换荧光强度间满足二次方关系,时间分辨荧光的研究表明荧光动力学曲线服从双e指数衰减.提出表面态辅助的双光子吸收模型是低激发强度上转换发光的主要机理.CdTe和CdT 关键词： CdTe量子点 CdTe/CdS核壳量子点 时间分辨荧光 上转换荧光     

On particles tunneling from the Taub-NUT-AdS black hole

This paper discusses tunneling of scalar particles and Dirac particles from the Taub-NUT-AdS black hole by the Hamilton--Jacobi equation, initially used by Angheben et al, and the Dirac equation, recently proposed by Kerner and Mann. This is performed in the dragging coordinate frame so as to avoid the ergosphere dragging effect. A general form is obtained for the temperature of scalar and Dirac particles tunneling from the Taub-NUT-Ads black hole, which is commensurate with other methods as expected.     

Efficient quantum secure communication scheme with one-time pad

In this paper, we proposed a novel quantum secure direct communication scheme with one-time pad in stabilizer formalism. Based on the reuse of qubit sequence, an efficient secure communication of secret messages without first producing a shared secret key can be achieved. One hence may find that the amount of private key needed for quantum communication is smaller than that in the general case. Therefore, the present protocol which is feasible with the present-day techniques may be applied to quantum communication with short-length encoding.     

Fermions tunneling from the Horowitz-Strominger Dilaton black hole

Based on the work of Kerner and Mann, fermions tunneling from the Horowitz-Strominger Dilaton black hole on the membrane is studied. Owing to the coupling among electromagnetic field, matter field and gravity field, the Dirac equation of charged particles is introduced, and according to that, the expected emission temperature is obtained. After the self-gravitational interaction is considered, it is found that the tunneling rate of fermions also satisfies the underlying Unitary theory as the case of scalar particles. Supported by the Natural Science Foundation of Sichuan Education Office (Grant No. 07ZC039)     

变加速直线运动黑洞中Weyl中微子的Hawking辐射

利用推广的乌龟坐标变换法研究了作变加速直线运动的Kinnersley黑洞中Weyl中微子的量子 热效应，导出了局部的事件视界面方程和Hawking温度以及中微子的热辐射谱.结果表明视界 的位置和温度不仅随时间变化，而且明显依赖于方位角. 关键词： Hawking辐射 Weyl中微子 动态Kinnersley黑洞 广义乌龟坐标变换     

HL-2A装置偏滤器室中性气体压强的初步研究

HL-2A装置上首次实现了偏滤器位形放电。采用专门研制的可在强磁场和强噪声环境下工作的快响应真空电离规对偏滤器室内的中性气体压强进行了测量,给出了HL-2A装置偏滤器有关结构的基础数据。初步研究了偏滤器位形和孔栏位形放电期间偏滤器室中性气体压强的特性。     

水平场景无畸变折反射全景成像系统透镜畸变的消除

采用短焦距透镜设计水平场景无畸变折反射全景成像系统,会使系统更加小型化,然而短焦距透镜的畸变会对系统成像产生影响。为此建立了具有径向畸变的相机模型;根据这一相机模型,研究了采用短焦距摄像头的水平场景无畸变折反射全景成像系统中,透镜畸变对系统成像的影响,结果表明短焦距透镜的畸变会对系统成像产生严重影响;为了消除透镜畸变的影响,对反射镜的设计进行了改进,在反射镜面形微分方程中包含了透镜畸变消除的参量;按新的方法,设计了一套由短焦距摄像头组成的水平场景无畸变折反射全景成像系统。     

电场催陈米酒核磁共振分析

以自行研制的设备对新产广东玉冰烧米酒进行催陈 (处理条件 :4 0kV·m- 1 的电场强度处理 180min ,5 0Hz) ;然后采用1 HNMR对新酒、电场催陈酒及成品酒进行了分析 ,研究发现新酒中甲基和亚甲基峰出现了 4个杂峰而其他样品没有 ,说明新酒中单分子与各种状态的缔合结构共存 ,其他各主要有机物质亦参与成峰 ;而关于羟基质子峰 ,新酒为平头峰 ,推断出溶液中有 2种羟基质子存在 ,一种参与形成缔合 ,另一种未参与缔合 ;成品酒为单一峰 ,说明溶液中形成了单一稳定的大分子缔合结构 ;电场处理酒样为不规则峰 ,反映出多种缔合状态共存 ,其主要缔合结构接近成品酒缔合结构     

Bi12TiO20纳米粉体的制备及其光吸收特性研究

以钛酸四丁酯和硝酸铋为原料 ,利用化学溶液分解法制备了Bi12 TiO2 0 纳米多晶粉体 .采用XRD和TEM对其结构和形貌进行了表征 .结合热重 差热 (TG DTA)分析 ,探讨了Bi12 TiO2 0 晶相的形成机理 .通过UV Vis漫反射谱的测定 ,研究了Bi12 TiO2 0 纳米晶粉体的光吸收特性 .结果显示 ,从组成为化学计量比的前驱液中可以很容易制得纯Bi12 TiO2 0 纳米晶粉体 ,该Bi12 TiO2 0 纳米晶粉体呈现了在很宽的波长范围内 (5 6 0～ 385nm )对光的吸收的特性 .     

Three types of maximally entangled states for a two-particle system

Foratwo-particle(spin1/2)systemthespinstateisdescribedusingavectorinafour-dimensionalHilbertspace.Inangularmomentumcouplingtheory[1],theangularmomentumuncouplingandcouplingrepresentationsareusuallyadopted.WhilethesimultaneouseigenstatesoftheCSCO(s1z,s2z),12,12,12and12,arechosenasthebasisofangularmomentumuncouplingscheme,thesimultaneouseigenstatesoftheCSCO(2,zSS),,SM(12=+Sss),arechosenasthebasisofangularmomentumcouplingscheme,1212100,2轾=-臌1212110,2轾=+臌121211,1,1.=-=Thefo…