非Lamb-Dicke近似下制备囚禁冷离子的振动相干态

根据非Lamb-Dicke近似下激光-离子相互作用动力学规律,讨论了如何利用一系列的激光脉冲来驱动冷离子,从而从运动基态出发获得一系列振动数态的宏观叠加态.具体研究了这些叠加态的Q函数、Wigner函数和它们的非经典特性,如压缩和反群聚效应等.结果表明,合适地调节各个所用激光的脉冲长度,所产生的叠加态能很好地逼近熟知的振动相干态. 关键词： Lamb-Dicke近似 叠加态 相干态 非经典特性     

离子晶体非简谐振动引起的光学非线性与增强吸收型光双稳

处理了光场与离子晶体的非简谐性振动之间的相互作用问题。导出了用简正坐标即声子模式所表达的非线性晶格动力学和非线性宏观极化。在旋转波近似下，得到在入射光驱动下光子－声子耦合体系的总的相干性哈密顿算符。     

制备囚禁冷离子的振动压缩量子态

基于非Lamb-Dicke近似下激光-离子相互作用的动力学规律,讨论了如何利用一系列的激光脉冲来驱动囚禁冷离子.从囚禁冷离子的运动基态出发获得压缩相干态、压缩奇偶相干态、压缩真空态等一系列的振动数态的叠加态.结果表明,只要适当地调节各个所用激光脉冲的长度和相位,总能很好逼近所需要的压缩量子态. 关键词： 囚禁冷离子 激光脉冲 压缩量子态     

囚禁离子非线性Rabi模型量子场熵演化特性

本文研究了基于单个囚禁离子与两束激光场相互作用的非线性Rabi模型中的纠缠动力学.利用Von-Neumann熵来表征纠缠度.通过数值模拟,详细讨论了Lamb-Dicke参数对量子场熵的影响.在单光子非线性Rabi模型中,随着Lamb-Dicke参数和初始平均光子数的增加,场熵的平均值并不单调增加.在双光子非线性Rabi模型中,场熵的时间演化是周期性振荡的.随着Lamb-Dicke参数的增加,场熵的周期振荡逐渐消失.对于较小的Lamb-Dicke参数,纠缠和退纠缠周期性地出现.     

非Lamb-Dicke近似下制备囚禁冷离子的振动相干态

根据非Lamb-Dicke近似下激光-离子相互作用动力学规律，讨论了如何利用一系列的激光脉冲来驱动冷离子，从而从运动基态出发获得一系列振动数态的宏观叠加态.具体研究了这些叠加态的Q函数、Wigner函数和它们的非经典特性，如压缩和反群聚效应等.结果表明，合适地调节各个所用激光的脉冲长度，所产生的叠加态能很好地逼近熟知的振动相干态.     

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。     

原子与多模辐射场作用的动力学性质的精确求解

本文精确求解了一个二能级原子与一个多模辐射场相互作用的动力学问题．文中没有用到旋转波近似和偶极近似,而是运用相干态展开技术,求得了相互作用过程中原子的上下两能级的粒子数随时间的变化情况,并讨论了系统中光子数随频率的分布．计算机的模拟计算给出了一些有意义的结果．     

类钠离子的电子碰撞电离截面

利用相对论修正扭曲波玻恩交换近似,计算了8个类钠离子的电子碰撞直接电离和激发自电离截面.基于这些结果,给出了计算类钠等电子系离子(18≤Z≤39)直接电离和激发自电离截面的高精度拟合公式.计算结果与现有的实验值和其他理论值比较,相当一致 关键词： 电离截面 组态相互作用 扭曲波玻恩交换近似 拟合公式     

ICRF快波模转换及快波传播

本文通过分析离子回旋频段(ICRF)快波在模转换区传播的物理过程,导出了一个新的快波近似——完全快波近似二阶波方程。数值计算表明,它能给出与求解高阶方程非常一致的结果,尤其是在弱回旋阻尼(k_1较小)情况下,完全快波近似比快波近似有更满意的结果。最后讨论了二次谐波加热和少数成份离子加热的实例。     

反铁磁自旋波对高温超导体的电阻特性的影响

针对含铜氧化物超导体，本引用一个传导电子与局域电子间的自旋耦合来描述Ｃｕ－Ｏ平面上巡游空穴与铜离子上的局域空穴之间的相互作用。采用自旋波近似，使该自旋耦合表现为巡游载流子与自旋波之间的相互作用，其形式与电－声相互作用类似，据此可得到因自旋波对载流子的散射引起的电阻与温度的依赖关系，其性质与电－声散射电阻相同。同时还引入具有自旋波子吸收或发射的层间遂穿散射过程，讨论了垂直方向上的电阻。所得结果与实     

Rogue wave observation in a water wave tank

The conventional definition of rogue waves in the ocean is that their heights, from crest to trough, are more than about twice the significant wave height, which is the average wave height of the largest one-third of nearby waves. When modeling deep water waves using the nonlinear Schr?dinger equation, the most likely candidate satisfying this criterion is the so-called Peregrine solution. It is localized in both space and time, thus describing a unique wave event. Until now, experiments specifically designed for observation of breather states in the evolution of deep water waves have never been made in this double limit. In the present work, we present the first experimental results with observations of the Peregrine soliton in a water wave tank.     

The reference wave solution for a two-frequency wave propagating in a random medium

In this work a new reference wave method for solving parabolic-type equations is proposed. The performance of the method is demonstrated by applying it to the equation governing the propagation of the two-frequency mutual coherence function in a random medium. An analytic solution is presented for arbitrary correlation properties of the medium. It is shown that when approximating the transverse structure function of the medium by a quadratic form, the solution reduces to the exact result derived previously. Extensions to more general types of media are considered.     

Large-amplitude plasma wave generation with a high-intensity short-pulse beat wave

A short-pulse laser beat wave scheme for advanced particle accelerator applications is examined. A short, intense (3-ps, >10(18)-W cm(-2)) two-frequency laser pulse is produced by use of a modified chirped-pulse amplification scheme and is shown to produce relativistic plasma waves during interactions with low-density plasmas. The generation of plasma waves was observed by measurement of forward Raman scattering. Resonance was found to occur at an electron density many times that expected, owing to ponderomotive displacement of plasma within the focal region.     

The reflection of a finite amplitude wave from a curvilinear unsteady shock wave

The reflection of a wave of finite amplitude from a curvilinear unsteady shock wave has been analyzed. A formula connecting reflected wave parameters with that of the incident wave, curvature and shock wave intensity has been obtained in closed form.     

Symmetry groups and spiral wave solution of a wave propagation equation

We study a third-order nonlinear evolution equation, which can be transformed to the modified KdV equation, using the Lie symmetry method. The Lie point symmetries and the one-dimensional optimal system of the symmetry algebras are determined. Those symmetries are some types of nonlocal symmetries or hidden symmetries of the modified KdV equation. The group-invariant solutions, particularly the travelling wave and spiral wave solutions, are discussed in detail, and a type of spiral wave solution which is smooth in the origin is obtained.     

一类非线性波动方程的精确行波解

利用改进的G’/G展开方法,借助于计算机代数系统Mathematica成功获得了一大类非线性波动方程一系列新的含有多个参数的精确行波解.这些解包括孤立波解、双曲函数解、三角函数解.     

Resonant interaction between a localized fast wave and a slow wave with constant asymptotic amplitude

An integrable Yajima-Oikawa system is solved in the case of a finite density, which corresponds to a slowly varying (long-wavelength) wave with finite amplitude at infinity and a localized fast-oscillating (short-wavelength) wave. Application of the results to spinor Bose-Einstein condensates and other physical systems is discussed.     

Excitation of upper-hybrid plasma wake wave by a low-frequency extraordinary electromagnetic wave

The excitation of upper-hybrid wake electrostatic wave by interaction of an extraordinary Gaussian wave propagating perpendicular to the external magnetic field in a cold homogeneous plasma is investigated using magnetohydrodynamics theory. The plasma oscillations can be excited due to the charge separation appeared by the ponderomotive force of the electromagnetic wave whose frequency is considered in the lower pass band. By obtaining the equation governing the plasma wake, the dependency of the wake amplitude on the physical parameters is studied. It is observed that larger wake oscillation takes place when the pulse length is approximately close to 3λ_p/π and the X-wave frequency is greater than ω_p, which means that the phase velocity is less than the speed of light in vacuum (v_p < c).