Large Detuning Interaction Between a Paul-Trapped Ion and a standing Wave Laser

An ultracold two-level ion which stays at its internal ground state, experiencing the standing wave of a large detuning laser in a Paul trap, has been studied in the Lamb-Dicke limit and near the weak excitation regime, with full consideration of the time dependence of the trapping potential.     

Analytical Solutions of a Trapped Ultracold Ion Experiencing a Travelling Wave Laser without Rotating Wave Approximation

In coherent state representation and in the absence of rotating wave approximation,the analytical forms of the eigenenergies and eigenfunctions of a trapped ultracold ion interactingwith a travelling wave laser are presented for some particular detunings. The differencebetween the standing wave laser and the travelling one radiating a trapped ultracold ion isalso pointed out.     

Propagation of General Wave Packets in Some Classical and Quantum Systems

In quantum mechanics the center of a wave packet is precisely defined as the center of probability. The center-of-probability velocity describes the entire motion of the wave packet. In classical physics there is no precise counterpart to the center-of-probability velocity of quantum mechanics, in spite of the fact that there exist in the literature at least eight different velocities for the electromagnetic wave. We propose a center-of-energy velocity to describe the entire motion of general wave packets in classical physical systems. It is a measurable quantity, and is well defined for both continuous and discrete systems. For electromagnetic wave packets it is a generalization of the velocity of energy transport. General wave packets in several classical systems are studied and the center-of-energy velocity is calculated and expressed in terms of the dispersion relation and the Fourier coefficients. These systems include string subject to an external force, monatomic chain and diatomic chain in one dimension, and classical Heisenberg model in one dimension. In most cases the center-of-energy velocity reduces to the group velocity for quasi-monochromatic wave packets. Thus it also appears to be the generalization of the group velocity. Wave packets of the relativistic Dirac equation are discussed briefly.     

Continued Fraction Approach to the Solution of a Trapped Ultracold Ion Interacting with a Standing Wave Laser without Rotating Wave Approximation

In coherent state representation and in the absence of rotating wave approximation, we present an approach to solve the interaction of a trapped ultracold ion with a standing wave laser by a continued fraction, within the Lamb-Dicke limit and the low excitation regime. It is shown that, the eigen-energies as well as the coefficients of the series of the eigenfunction can be obtained rapidly from the continued fraction.     

Analytical Solution for an Ultracold Trapped Ion at the Node of the Standing Wave Laser Without Rotating Wave Approximation

A method of solving an ultracold trapped ion at the node of the standing wave laser without rotating wave approximation is proposed and the analytical forms of the eigenfunctions and eigenenergies of the system are presented.     

Inversion of an Atomic Wave Packet in a Circularly Polarized Electromagnetic Wave

We study behavior of an atomic wave packet in a circularly polarized electromagnetic wave,and particularly calculate the atomic inversion of the wave packet.A general method of calculation is presented.The results are interesting.For example,if the wave packet is very narrow or /and the interaction is very strong,no matter the atom is initially in its ground state or excited state,the atomic inversion approaches zero as time approaches infinity.If the atom is initially in its ground state and excited state with the probability 1/2 respectively,and if the momentum density is an even function,then the atomic inversion equals zero at any time.     

Analytical Solution for an Ultracold Trapped Ion at the Node of the Standing Wave Laser Without Rotating Wave Approximation

A method of solving an ultracold trapped ion at the node of the standing wave laser without rotating wave approximation is proposed and the analytical forms of the eigenfunctions and eigenenergies of the system are presented.     

A Study of a Confined Hydrogen Negative Ion

The ground and three low-excited states of the hydrogen negative ion confined by a spherical harmonic oscillator potential are studied employing the adiabatic hyperspherical approach method. Total energies are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values.     

Wave Packets in a Magnetic Field

A Gaussian wave packet confined to move on a plane perpendicular to a magnetic field remains a Gaussian wave packet in its time evolution. The average position and momentum follow the Ehrenfest equations which are identical to the classical Hamilton equations. A set of nonlinear equations decoupled from the Ehrenfest equation is derived for the parameters describing the time evolution of the density distribution and phases of a wave packet. Explicit solutions are then obtained when the "internal" angular momentum of the wave packet vanishes. In this case it is shown that the motion of the wave packet is a superposition of a translational motion, a rotation and a vibration.     

F+HCl/DCl反应散射的量子含时波包

在Deskevich等人最近构建的势能面上，利用量子含时波包方法，研究了F+HCl/DCl的反应散射动力学．在总角动量J=0的情况下，得出了这两个反应具有不同初始振转态条件下的总反应几率．计算结果表明，对于这两个反应，反应物的转动激发态可以明显的提高反应几率，对于F+HCl反应这种提高尤其明显．而振动激发只是对降低碰撞能反应阈值有帮助，对总的反应几率几乎没有任何影响．另外，这两个反应的进行途径有明显的转动自由度部分．在含有较轻的氢原子的F+HCl反应中，总反应几率中所呈现的量子共振和隧穿效应较之F+DCl     

H-在金属面附近光剥离的波包动力学研究

利用波包演化和自关联函数方法对H^-在金属面附近光剥离的波包动力学进行了研究.结果表明,金属面附近光剥离电子的波包演化和回归结构与H^-到金属面的距离、激光脉冲的脉冲宽度和初始动量都有一定的关系.因此,可以通过改变离子表面距离和激光脉冲的参数对光剥离电子的动力学性质进行调控研究.除此之外,光剥离电子的镜像态寿命对波包的演化和自关联函数也会产生一定的影响:考虑镜像态寿命的影响时,随着时间的演化,波包概率密度的振幅逐渐减小,波包整体上有明显的衰减,寿命对波包演化过程中的干涉有削弱的作用;通过对电子波包的自关联函数研究,发现无限长寿命的电子波包有很好的量子回归现象,而当考虑寿命因素后光剥离电子波包随着时间的演化会发生周期性的坍塌和扩散,经过一段时间后,该回归现象消失.本文的理论研究可以为表面附近电子波包动力学的实验研究提供一定的参考价值. 关键词： 波包 演化和回归 自关联函数 金属面     

Dynamical Characteristics of Traveling Wave Packets of Total Electron Content Disturbances

Using the COPHASE method and the GPS interferometry method for travelling ionospheric disturbances, we analyze in detail the spatio-temporal properties of travelling wave packets (TWP) of total electron content (TEC) disturbances. The analysis is performed on the example of a clearest TWP manifestation observed in California, USA, in October 18, 2001, using the GLOBDET technique, developed at the Institute of Solar-Terrestrial Physics of the Siberian Branch of RAS for global detection and monitoring of natural and technogenic ionospheric disturbances on the basis of TEC variations retrieved from the global network of GPS receivers. In the time domain, TWPs are quasi-periodic TEC oscillations of duration about 1 h, period of 10–20 min, and amplitude exceeding that of the background TEC fluctuations by at least one order of magnitude. The velocity and direction of TWP motion are similar to those of mid-latitude mesoscale travelling ionospheric disturbances, as obtained earlier from the analysis of phase parameters of HF radio signals and the signals of geostationary satellites and discrete space radio sources.     

Ion pickup by intrinsic low-frequency Alfven waves with a spectrum

<正>Ion pickup by a monochromatic low-frequency Alfven wave,which propagates along the background magnetic field,has recently been investigated in a low beta plasma(Lu and Li 2007 Phys.Plasmas 14 042303).In this paper, the monochromatic Alfven wave is generalized to a spectrum of Alfven waves with random phase.It finds that the process of ion pickup can be divided into two stages.First,ions are picked up in the transverse direction,and then phase difference(randomization) between ions due to their different parallel thermal motions leads to heating of the ions.The heating is dominant in the direction perpendicular to the background magnetic field.The temperatures of the ions at the asymptotic stage do not depend on individual waves in the spectrum,but are determined by the total amplitude of the waves.The effect of the initial ion bulk flow in the parallel direction on the heating is also considered in this paper.     

The Construction of Dirac Wave Packets for a Fermionic Particle Non-Minimally Coupling with an External Magnetic Field

We shall proceed with the construction of normalizable Dirac wave packets for fermionic particles (neutrinos) with dynamics governed by a “modified” Dirac equation with a non-minimal coupling with an external magnetic field. We are not only interested on the analytic solutions of the “modified” Dirac wave equation but also on the construction of Dirac wave packets which can be used for describing the dynamics of some observable physical quantities which are relevant in the context of the quantum oscillation phenomena. To conclude, we discuss qualitatively the applicability of this formal construction in the treatment of chiral (and flavor) oscillations in the theoretical context of neutrino physics. PACS numbers: 02.30.Cj, 03.65.Pm     

一般幂指数中心势作用下的波包回归和部分回归

利用WKB近似和自关联函数方法,我们研究了一般幂指数中心势V(r)=γrk (-20)作用下波包的回归和部分回归.对于排斥势(γ>0, k>0), 势是一长程势,量子化能级结构中只有一个量子数,波包的回归结构和一维幂指数势的情况类似.这一结果表明能级结构相同的体系具有相同的波包回归结构.对于吸引势,能级结构中有两个量子数, 当 k取不同的值时,波包的回归结构不同.对于库仑吸引势,波包回归和部分回归出现;但是对于其它的k值, 经过一段时间后,波包出现坍塌.本文的研究对于探讨里德堡原子和分子中电子运动的经典极限提供了一个新的方法.     

一般幂指数中心势作用下的波包回归和部分回归

利用WKB近似和自关联函数方法,我们研究了一般幂指数中心势V(r)=rk (-20)作用下波包的回归和部分回归。对于排斥势(>0, k>0), 势是一长程势,量子化能级结构中只有一个量子数,波包的回归结构和一维幂指数势的情况类似。这一结果表明能级结构相同的体系具有相同的波包回归结构。 对于吸引势,能级结构中有两个量子数, 当 k取不同的值时,波包的回归结构不同。对于库仑吸引势,波包回归和部分回归出现; 但是对于其它的k值, 经过一段时间后,波包出现坍塌。本文的研究对于探讨里德堡原子和分子中电子运动的经典极限提供了一个新的方法。     

行波激光场中囚禁离子的布居反转

研究了以波激光场中单个囚禁离子布居反转的动力学特性，分别讨论了失谐参数、质心振动声子场的初始值以及Lamb-Dicke参数对离子布居反转的崩塌和回复现象的影响。     

Experimental Study on Wave Characteristics of Stilling Basin with a Negative Step

Stilling basin with a negative step is an important structure in hydraulic systems, because it can avoid atomization and decrease scouring problems. Although stilling basins with a negative step have attracted much attention from researchers, few researchers have focused on the wave characteristics. In this research, an experimental study on the wave characteristics of stilling basins with a negative step was carried out. The wave height, average period, wave probability density and power spectrum along the flow direction of different stilling basins with a negative step were described based on the wave theory, and the results indicate discharge and step height have a significant effect on the wave characteristics. The relationships between the different characteristic wave heights, and the empirical formula for the relative characteristic wave height are obtained. Finally, the dimensionless standard deviation at the end of the stilling basin with a negative step is linearly related to the flow-energy ratio and the relative step height under B-jump.     

Dynamics of Two-Level Trapped Ion in a Standing Wave Laser in Noncommutative Space

We study the dynamics of a two-level trapped ion in a standing wave electromagnetic field in two-dimensional （2D） noncommutative spaces in the Lamb-Dicke regime under the rotating wave approximation. We obtain the explicit analytical expressions for the energy spectra, energy eigenstates, unitary time evolution operator, atomic inversion, and phonon number operators. The Rabi oscillations, the collapse, and revivals in the average atomic inversion and the average phonon number are explicitly shown to contain the information of the parameter of the space noncommutativity, which sheds light on proposing new schemes based on the dynamics of trapped ion to test the noncommutativity.