Completely solid-state LD-side-pumped Nd:YAlO<Subscript>3</Subscript> CW blue laser with intracavity frequency tripling

We report a completely solid-state continuous-wave (CW) blue laser operating at 447 nm utilizing intracavity frequency tripling of an LD-side-pumped Nd:YAlO₃ (Nd:YAP) laser operating at 1341.4 nm. An LBO crystal with type-I critical phase matching and a KTP crystal with type-II critical phase matching (CTM) were used for the second harmonic generation (SHG) and the third harmonic generation (THG), respectively. In view of the analysis of the cavity stability, a four-mirror folded cavity was designed and the output characteristics were theoretically analyzed. Experimental characteristics obtained were shown to be in agreement with the theoretical analysis. The maximum output power of the 447 nm CW blue laser reached 114 mW, which corresponds to a red-to-blue conversion efficiency of 9%.     

Complex-scaling treatment for high-lying doubly excited resonances for screened Coulomb helium atom

This work presents an investigation on the doubly excited ¹S ^e autoionizing states of screened helium atom lying below the n = 4 threshold of the He⁺ ion. The potential generated in this system is represented by a Yukawa type potential. We have employed complex-coordinate rotation method, as it is a powerful scheme to study high lying resonances. Hylleraas type wave function is used to consider the correlation effect between all the charged particles. Our resonance parameters for the resonances lying below the He⁺ (n = 2) threshold agree well with those of the existing calculations by using the stabilization method. Resonances associated with higher thresholds are new calculations. All the present results are well converged with basis length N = 444.     

Expansion dynamics of an array of high density Bose-Einstein condensates produced in a 1D CO<Subscript>2</Subscript> laser optical lattice

We discuss the expansion dynamics under mean-field repulsion of an array of ⁸⁷Rb Bose-Einstein condensates produced in an all-optical scheme involving 1D lattice with nearly 10⁵ atoms, after fast evaporative cooling of just about 1 s. Single site occupation exceeds 2 × 10⁴ in our experiments. The possibility of transition to two-dimensionality was also investigated. The expansion behavior of the high density multiple micro-condensates produced directly in the CO₂ laser 1D optical lattice, with a lattice spacing of 5.3 μm, agrees well with a numerical simulation based on the mean-field theory.     

Bianchi Type <Emphasis Type="Italic">VI</Emphasis><Subscript>0</Subscript> Magnetized Barotropic Bulk Viscous Fluid Massive String Universe in General Relativity

A model of a cloud formed by massive strings is studied in the context of the usual general relativity. This model is used as a source of Bianchi type VI ₀ massive with magnetic field and bulk viscosity. To get a determinate model, we assume that the expansion (θ) in the model is proportional to the shear (σ) and also the fluid obeys the barotropic equation of state. The behaviour of the models from physical and geometrical aspects in presence and absence of magnetic field and bulk viscosity is discussed.     

Charge,Geometry, and Effective Mass in the Kerr-Newman Solution to the Einstein Field Equations

It has been shown that for the Reissner-Nordström solution to the vacuum Einstein field equations charge, like mass, has a unique space-time signature (Marsh, Found. Phys. 38:293–300, 2008). The presence of charge results in a negative curvature. This work, which includes a discussion of effective mass, is extended here to the Kerr-Newman solution.     

渤海近岸水体后向散射系数反演模型

水体后向散射系数bb是重要的海洋光学参数,在以悬浮物为主要组分的浑浊二类水体中,其对于水体光学性质起着决定性的作用,该参数的遥感反演对于海洋光学与水色遥感研究具有重要意义.利用2005年渤海近岸水体实测数据集,建立了基于水体遥感反射率光谱数据的后向散射系数bb(λ)经验反演模型(λ=442 nm,488 nm,532 nm,589 nm,676 nm),经实测数据检验,bb(442)和bb(589)反演平均相对误差约为30%;bb(488)和bb(676)反演半均相对误差优于40%;bb(532)反演半均相埘误差约为57%.通过分析模型对于输入误差的敏感性发现,当输入端引入±5%的误差时,模型反演值的误差波动在绝大多数情形下可控制在±10%以内,模型足稳定可靠的.模型适用于渤海近岸浑浊水体,可用丁水体光学参数的时空分布特征分析以及基丁固有光学参数的水色组分遥感反演.     

基于CSIFT的彩色图像配准技术研究

图像配准在计算机视觉、遥感、医学诊断与治疗、环境监测等领域有广泛的研究应用.目前,多数算法是将彩色图像转化为灰度图后再配准,色彩信息的丢失可能会引起误配准.为此,提出一种基于CSIFT(Colored scale invariant feature transform)的彩色图像配准方法,求出彩色图像各个位置处的颜色不变最,以颜色不变量作为输入图像,再提取特征点并描述特征点周围的信息,通过最近邻匹配法求出图像问的匹配对,最后利用匹配的特征求取图像间的变换参数及配准后图像.实验结果表明,对彩色图像进行已知参数值变换时,该算法能得到精度高、误差小的计算结果;对变换关系末知的彩色图像,也能准确地求出图像间的映射关系;且多数情况下运行速度较SIFT(Scale invariant feature transform)快.     

A Categorical Framework for the Quantum Harmonic Oscillator

This paper describes how the structure of the state space of the quantum harmonic oscillator can be described by an adjunction of categories, that encodes the raising and lowering operators into a commutative comonoid. The formulation is an entirely general one in which Hilbert spaces play no special role. Generalised coherent states arise through the hom-set isomorphisms defining the adjunction, and we prove that they are eigenstates of the lowering operators. Generalised exponentials also emerge naturally in this setting, and we demonstrate that coherent states are produced by the exponential of a raising morphism acting on the zero-particle state. Finally, we examine all of these constructions in a suitable category of Hilbert spaces, and find that they reproduce the conventional mathematical structures.     

Spin–gravity coupling and gravity-induced quantum phases

External gravitational fields induce phase factors in the wave functions of particles. The phases are exact to first order in the background gravitational field, are manifestly covariant and gauge invariant and provide a useful tool for the study of spin–gravity coupling and of the optics of particles in gravitational or inertial fields. We discuss the role that spin–gravity coupling plays in particular problems.