一种可压缩流动的高阶加权紧致非线性格式(WCNS)的加速收敛方法

以高超声速粘性绕流的数值模拟为例,研究LU-SGS、高斯-赛德尔点松弛、线松弛以及GMRES等隐式求解方法在空间项采用高阶精度格式WCNS离散时的收敛性,并对GMRES(generalized minimal residual)方法中的子迭代影响作了对比计算.结果表明,采用准确的解析雅克比矩阵的点、线松弛的收敛速度优于LU-SGS,以线松弛为预处理的GMRES算法具有良好的收敛特性.     

微型光学偶极阱中单原子相干操控Rabi振荡的实现及其应用

文章综述了Rabi振荡的基本原理以及微型光学偶极阱中单原子相干操控Rabi振荡的研究进展,同时介绍了其在单光子源、量子寄存器、量子计算等方面的应用,并简要介绍了作者所在小组在微型光学偶极阱中单原子操控方面的实验进展.     

Interaction of a Two-Level Atom with the Morse Potential in the Framework of Jaynes-Cummings Model

A theoretical study of the dynamical behaviors of the interaction between a two-level atom with a Morse potential in the framework of the Jaynes Cummings model （JCM） is discussed. We show that this system is equivalent to an intensity-dependent coupling between the two-level atom and the non-deformed single-mode radiation field in the presence of an additional nonlinear interaction. We study the dynamical properties of the system such as, atomic population inversion, the probability distribution of cavity-field, the Mandel parameter and atomic dipole squeezing. It is shown how the depth of the Morse potential can be affected by non-classical properties of the system. Moreover, the temporal evolution of the Husimi-distribution function is explored.     

Spatial coherences of the sound pressure and the particle velocity in underwater ambient noise

The spatial coherences were investigated between the sound pressure and the three orthogonal components of the particle velocity in underwater ambient noise. Based on the ray theory, integral expression was derived for the spatial coherence matrix of the sound pressure and the particle velocity in a stratified ocean with dipole noise sources homogenously distributed on the surface. The integrand includes a multiplying factor of the vertical directivity of the noise intensity, and the layered ocean environment affects the spatial coherences via this directivity factor. For a shallow water environment and a semi-infinite homogenous medium, the coherence calculation results were given. It was showed that the sound speed profile and the sea bottom could not be neglected in determining the spatial coherences of the ambient noise vector field.     

高剥离类镁等电子序列的磁偶极M1和电四极E2光谱跃迁理论研究

利用全相对论性多组态Dirac-Fock广义平均能级方法，系统地计算了类镁离子3s3p磁偶极Ml^3P2--^3P1和电四极E2 ^2P2--^3P0(Z=20-103)光谱跃迁的能级间隔、跃迁几率和振子强度。计算中考虑了原子核的有限体积效应，进行了高阶Breit修正和QED修正，所得到的能级间隔和最近的实验数据及理论计算值进行了比较。计算结果表明：高原子序数的高荷电离子的磁偶极矩M1和电四极矩E2跃迁几率和中性原子的电偶极E1的相当，在ICF和MCF高温激光等离子体中，磁偶极矩M1和电四极矩E2跃迁过程不容被忽视。     

北京τ–c工厂(BTCF)快速蒙特卡罗模拟方法的开发和应用

参考国内外现有的τ-c工厂及其探测器的设计结果,给出了BTCF探测器的总体指标. 根据这些指标设计并开发了用于BTCF物理研究的快速蒙特卡罗模拟方法,并用此方法对一系列重要的物理课题进行了蒙特卡罗模拟. 文中描述了该模拟方法的设计思想、程序流程以及这种方法在BTCF可行性研究乃至预制研究阶段的优越性,同时也给出了对若干重要物理问题的模拟结果. 从而论证了建造BTCF的必要性和不可替代性.     

自旋相关相对论修正对重夸克偶素性质的研究

自旋相关的相对论修正对有限温度下重夸克偶素的结合和分解的影响进行了讨论,结果表明精细和超精细相互作用特影响对重夸克偶素性质的预言,特别是对ηc和J/ψ起着明显的作用.     

金纳米粒子光学性质中的尺寸和形状效应

纳米尺度的金属及半导体呈现出特殊的光学、电学及磁学性质,采用近年发展起来的离散偶极近似(DDA)的方法,我们分析了金纳米粒子的尺寸及形状对其光学性质的影响。粒子周围介质的影响在文中亦作了分析。计算结果显示,金纳米粒子的等离子体吸收带同时受到粒子尺寸和形状的影响,但来自形状的影响更为明显。与米氏理论及扩展的甘氏理论相比较,DDA方法在粒子尺寸不再远小于入射光波长的时候更准确,并能应用于任何形状的纳米粒子。理论计算与实验结果能较好的吻合。     

Entanglement Transfer from Two-Mode Squeezed Vacuum State Field to Two Spatially Separated Atoms in Two-Photon Processes

We investigate the influence of the Stark shift on the entanglement transfer from the two-mode squeezed vacuum state field to two spatially separated atoms in two-photon processes. Our results show that the Stark shift plays an important role in such entanglement transfer. We find that when the Stark shift parameter r is small, the degree of entanglement between the two atoms increases with the increasing of the squeezing parameter ξ first, and after achieving its maximal value, the degree of entanglement will decrease to zero with the increasing of ξ; while for big r, E will increase with the increasing of ξ.