Atom-photon entanglement in the system with competing k-photon and l-photon transitions

We have investigated the evolution of the atomic quantum entropy and the entanglement of atom-photon in the system with competing k-photon and l-photon transitions by means of fully quantum theory, and examined the effects of competing photon numbers （k and l）, the relative coupling strength between the atom and the two-mode field （A/g）, and the initial photon number of the field on the atomic quantum entropy and the entanglement of atom-photon. The results show that the multiphoton competing transitions or the large relative coupling strength can lead to the strong entanglement between atoms and photons. The maximal atom-photon entanglement can be prepared via the appropriate selection of system parameters and interaction time.     

双间隙输出腔开放腔的高频特性分析

 建立了S波段相对论速调管放大器双间隙输出腔开放腔的3维模型。采用时域有限差分法,通过监测激励电流源的响应计算了该双间隙输出腔的谐振频率、有载Q值、场分布以及特性阻抗,并分析了腔体结构尺寸对谐振频率、有载Q值和特性阻抗的影响。研究表明：腔体半径对开放腔的谐振频率影响很大,耦合孔尺寸对腔体谐振频率的影响较小;随着耦合孔张角增加,有载Q值逐渐减小;随着腔体半径增大、间隙的减小,腔体特性阻抗降低。研究结果可为S波段强流相对论速调管放大器双间隙输出腔的设计提供理论依据。     

用于原子能级结构研究的激光共振电离光谱系统

激光共振电离光谱技术是一种利用一路或多路激光将待测原子选择性共振激发与电离,通过测量离子信号来研究原子能级结构的光谱技术。研建了一套激光共振电离光谱装置,用于原子高激发态能级结构参数的测量。分别从该装置的总体结构、关键技术和应用实例等方面进行了详细介绍。该套装置主要包括高调谐精度的染料激光器系统、高效的激光离子源系统和高分辨率的飞行时间质量分析器。染料激光器系统包括3台多纵模可调谐染料激光器和1台单纵模可调谐染料激光器,均为脉冲工作方式,重复频率为10 kHz,泵浦源均为532 nm的Nd∶YAG固体激光器。激光离子源系统包括原子化源、激光与原子相互作用区和离子光学透镜组三部分组成,样品在原子化源中被电加热实现原子化,喷射出的原子被激光选择性激发、电离,产生的离子被离子传输透镜整形成能量分散小、束窄的离子束。飞行时间质量分析器采用了反射式结构设计、脉冲垂直推斥技术和偏转板调节技术。利用此装置,实验测定了U原子的自电离态光谱,获得了U原子一条较佳的三色三光子共振电离路径,对应激光的波长分别为591.7,565.0和632.4 nm。此系统还可用于测量同位素位移和原子超精细结构等参数。另外,由于此系统中联用了质量分析器,因此可用于样品多元素分析、痕量元素分析、同位素丰度分析。     

Bearings-Only Target Motion Analysis Using a Dual-Waveband Infrared System

Infrared systems are widely used for target detection, designation and tracking. For example, an Infrared Search and Track (IRST) system, as a typical airborne or shipboard detecting device, is widely equipped for the remote target detection and tracking. In recent years, the problem of target motion analysis (TMA) and tracking has been studied increasingly extensively. In an airborne infrared system, the problem becomes more difficult due to absence of range information. In this paper, the infrared model and motion model of typical aerial targets are described. An airborne dual-waveband IRST system, which is quite familiar nowadays, is choosed for implementation of target motion analysis. Based on the above, a novel and more practical algorithm of target tracking via bearings-only measurements is formed and the major parameters are defined according to a typical airborne dual-waveband IRST system. Finally, data simulation is implemented, and the results demonstrate the new algorithm has a better performance than before for bearings-only target tracking.     

Marginal Fermi liquid resonance induced by a quantum magnetic impurity in d-wave superconductors

We consider a model of an Anderson impurity embedded in a d(x(2)-y(2))--wave superconducting state to describe the low-energy excitations of cuprate superconductors doped with a small amount of magnetic impurities. Because of the Dirac-like energy dispersion, a sharp localized resonance above the Fermi energy, showing a marginal Fermi liquid behavior ( omega ln omega as omega-->0), is predicted for the impurity states. The same logarithmic dependence of self-energy and a linear frequency dependence of the relaxation rate are also derived for the conduction electrons, characterizing a new universality class for the strong coupling fixed point. At the resonant energies, the spatial distribution of the electron density of states around the magnetic impurity is also calculated.     

加性噪声对激光一级相变类比的影响

从单模激光场的增益－噪声模型出发,导出了激光场定态强度分布函数,研究了定态分布函数的极值点随加性噪声、乘性噪声和注入信号的变化情况。结果表明,乘性噪声是使激光系统出现一级相变类比的关键因素,注入信号使相变行为减弱,而加性噪声却使得定态分布中极值点的数量和位置出现来回跳跃式变化。     

锶460.7 nm法拉第色散光学滤波器的滤波特性分析

分析了处于夫琅禾费暗线的Sr 460.7nm法拉第色散光学滤波器线翼和线芯工作的滤光特性,研究了磁场,温度和池长对滤波特性的影响,讨论了在其最佳的工作条件下,线芯透射率为95％,线宽为1．47GHz。     

红外光谱统计波长选择方法用于废气检测

为了从含有噪声的大气红外光谱中提取微量待测污染组分的定量特征,进而建立校正模型,本文提出了一种基于统计理论的波长选择方法。该方法针对待测组分,在对光谱各波长位置的噪声强度进行统计估计的基础上,提出了选择最佳波长子集的目标函数。该目标函数包含波长子集的噪声和长度参数,这使得在最小化模型误差的同时也防止了模型规模的无限制膨胀。为了检验该方法的性能。文章利用含背景噪声的实测光谱数据针对三种气体进行了波长选择,并利用神经网络技术分别建立了校正模型。实验结果与波长子集的优化结果相符,所选择的波长子集的长度不足光谱波长总点数的2％,同时,光谱中的噪声也在校正模型中得到了明显的抑制。实验结果证明了该波长选择方法的有效性。     

温度对涂有溶胶-凝胶多层干涉膜的卤钨灯光谱的影响

本文叙述了两个问题.首先,采用溶胶-凝胶浸渍水解法在H4汽车灯上制备了多层干涉膜.该膜层温度升高使这种灯透过膜层的光谱有所移动,于是引起灯发射光谱的变化.其次,我们研究了温度对膜材料光学性质的影响.     

光折变晶体中光诱导波导的折射率分布

分别讨论了亮孤子和暗孤子在光折变晶体中诱导波导的折射率分布,结果表明光诱导波导的折射率分布除与光强的倒数有关外,还与光强对数的一阶导数有关.后者对折射率的影响引起波导折射率的非对称性分布.