Non-Markovian and Markovian Dynamics of a V-type Three-Level Atom

The reduced dynamics of a V-type three-level atom in a structure reservoir is presented,which has the exact solution in certain special condition.The Markovian and non-Markovian master equations for this composite system are solved and compared with the exact solution.The solving approach can be directly generalized to the solution of a V-type multilevel system dynamics interacting with a reservoir.The results further testify that these two kinds of master equations are exploited in different coupling regime,providing guidance for further application of these variants master equations to solve multilevel system dynamics without the exact solution.     

Non-Markovian relaxation of a three-level system: quantum trajectory approach

The non-Markovian dynamics of a three-level quantum system coupled to a bosonic environment is a difficult problem due to the lack of an exact dynamic equation such as a master equation. We present for the first time an exact quantum trajectory approach to a dissipative three-level model. We have established a convolutionless stochastic Schr?dinger equation called the time-local quantum state diffusion (QSD) equation without any approximations, in particular, without Markov approximation. Our exact time-local QSD equation opens a new avenue for exploring quantum dynamics for a higher dimensional quantum system coupled to a non-Markovian environment.     

A semi-classical approach to two-frequency solitons in a three-level cascade atomic system

A semi-classical theory of two intense optical fields interacting with a third-order non-linear medium composed of a three-level cascade atomic system is presented. It is predicted that non-linear atom-field interactions allow the formation of two-frequency bright, dark and grey spatial solitons. We demonstrate through numerical simulations and analytic stability analysis that the bright and grey solitons are stable.     

Influence of multiphoton detunings from resonance on adiabatic processes in a five-level system

The Schrödinger equation for a five-level system has been analyzed numerically for different values of multiphoton detuning from exact resonances. The range of admissible deviations for which the effect of multiphoton detunings on the eigenstate of the interaction Hamiltonian imitating a three-level system is insignificant has been determined. The effective population transfer and the possibility of double storage of optical information have been demonstrated.     

原子玻色-爱因斯坦凝聚体对V型三能级原子激光压缩性质的影响

利用格子液体方法对V型三能级原子玻色-爱因斯坦凝聚体与双模压缩相干态光场相互作用系统的哈密顿量进行分析,发现文献中对原子间相互作用部分的处理有不合理之处,从而对该哈密顿量作出了改进并研究了V型三能级原子玻色-爱因斯坦凝聚体与双模压缩相干态光场相互作用系统中原子激光的两个正交分量的压缩性质.研究表明:V型三能级原子玻色-爱因斯坦凝聚体中光场-原子相互作用强度对原子激光的两正交分量的涨落有明显的影响. 关键词： 玻色-爱因斯坦凝聚 V型三能级原子 压缩相干态 压缩原子激光     

Self-consistent solutions of the problem of the interaction of a two-frequency field with a system of three-level atoms in the form of a phase-modulated simulton and a Raman soliton

This paper discusses features of the interaction of a system of three-level atoms with a bichromatic electromagnetic field. Steady-state solutions are found in the form of unimodal and nonunimodal solitary waves corresponding to a pair of pulses in the form of a simulton or a Raman soliton. An analytic form of the solutions is found, corresponding to a phase-modulated simulton and a Raman soliton. The conditions are determined for exciting them. The resulting solutions are of interest from the standpoint of the mechanism for forming the two-frequency coupled excitations observed in various experiments. Zh. éksp. Teor. Fiz. 113, 747–762 (February 1998)     

Theory of two-frequency excitation in<Superscript>14</Superscript>N NQR

A simple and effective technique for calculating the transient signals in three-level spin systems irradiated at one and two frequencies is described. All possible signals are presented and discussed. The application of the two-frequency excitation technique for the investigation of the inhomogeneity of the crystalline lattice is suggested.     

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.     

V型三能级原子双模光场系统中光场压缩性质

本文利用格子液体方法对文献中给出的V型三能级原子玻色-爱因斯坦凝聚体与双模压缩相干态光场相互作用系统的哈密顿量进行分析,发现文献中对原子间相互作用部分的处理有不合理之处,从而对该哈密顿量作出了改进并研究了V型三能级原子双模光场系统中光场压缩性质.结果表明:光场两正交分量交替呈现周期性压缩现象,其压缩深度与光场初始压缩因子密切相关,而压缩时间与双模光场的频率有关. 关键词： 玻色-爱因斯坦凝聚 V型三能级原子 压缩相干态 双模压缩态光场     

在相干态表象中精确求解无旋波近似的Jaynes-Cummings模型

在相干态表象中精确求解了无旋波近似的Jaynes-Cummings模型，并导出了相应的限制性条件．所求得的解析解与用微扰论求得的近似解比较，当微扰级数取无穷时所得结果一致．本文的方法能方便地推广到三能级系统的讨论． 关键词：     

The spin-1 Ising model on a two-layer Bethe lattice with FM/AFM interactions

Two-layer Bethe lattice with the Ising spins of the top layer having only ferromagnetic (FM) interactions and the bottom layer having only antiferromagnetic (AFM) interactions are allowed to interact with the interlayer interaction of either FM or AFM type. The model is studied by using the exact recursion relations in a pairwise approach for given coordination numbers q=3, 4 and 6 with equal external magnetic fields acting on the layers. The phase diagrams of the model are obtained on different planes for given system parameters by studying the ground state (GS) phase diagrams and the thermal variations of the order-parameters and the response functions, i.e. the susceptibility and the specific heat, in detail. The model presents second- and first-order phase transitions, and where their lines are combined is the tricritical point. The critical end points also exist. The reentrant behavior is also seen when the model presents two Néel temperatures.     

The spectral maximum of synchrotron radiation

A three-level system is considered as a simplest example where a possibility of solving the spectral problem is observed. We thoroughly analyze the relation between the amount of radiation emitted by the particle during the transitions to the first excited state and to the ground state. Generalizing basic expressions we can follow the evolution of spectral maximum. It turns out there is a condition for radiation maximum to stay at highest harmonic.     

Trapping State in a System of Single Three-level Trapped Ion Driven by External Fields

We investigate the interaction of a single three-level trapped ion with two laser beams. By applying a unitary transformation and a small rotating transformation, an exact solution to this quantum system is obtained without performing the Lamb-Dicke approximation, and the trapping state is observed.     

基于光栅投影的轮廓测量改进方法

传统傅里叶变换轮廓方法(FTP)在测量表面突变的物体时,受物体高度变化所引起的非截断相位变化的影响,相位难以正确展开。利用双频光栅投影可以解决这一问题。在总结了传统测量方法与双频光栅测量方法的基础上,提出采用彩色复合光栅投影的测量方法。该方法只需一次采集,就能消除图像背景分量与高次分量对测量的影响,在扩大测量范围的同时可达到双频技术测量突变效果。最后,对3种方法的实际测量结果作了对比分析,证明彩色复合光栅投影方法得到的测量精度最高。     

Coulomb broadening of nonlinear resonances in a field of intense standing wave

The problem of probe-field spectrum is considered for a three-level ion placed in a field of an intense standing light wave. The ion interaction with plasma and the velocity-changing Coulomb scattering are taken into account within the weak-collision model. The system of kinetic equations for the density matrix is solved by the expansion in spatial harmonics and eigenfunctions of the collision operator. The profile of nonlinear addition to the probe-wave absorption is determined for various values of the effective ion-ion collision frequencies and various amplitudes and frequencies of standing wave. It is shown that the broadening of the central nonlinear structure in the spectrum is caused by the Coulomb dephasing effect. The computational results are in qualitative agreement with the available experimental data.     

纳米级精度分光路双频干涉度量系统的设计

为完成快速、精确的外观轮廓度量,设计了一种新型纳米级精度分光路双频干涉度量系统。系统由低频差双频激光干涉度量模块和微探头及二维工作台两部分组成。微探针以轻敲式接近样品至几十纳米时,受原子力作用发生偏转,利用双频干涉模块度量其纵向偏转量,并对样品进行梳状式度量得到外观形貌。根据双频激光的实际光源,对原有双频干涉度量理论进行了改进提高。进行了系统组建和实验验证。结果表明:系统具有纳米级精度,可用于超精样品外观轮廓度量。     

The kinetic energy partition method applied to a confined quantum harmonic oscillator in a one-dimensional box

A new, physically motivated, basis set expansion method for solving quantum eigenvalue problems with competing interaction potentials is presented. In contrast to the usual dissection of the potential energy into unperturbed and perturbing terms, we divide the kinetic energy into partial terms by modifying the mass factor. The partition scheme results in partial kinetic energies with their effective mass factors. By distributing each partial kinetic energy to a respective potential energy to form a subsystem, the total Hamiltonian is written as the sum of subsystem Hamiltonians. Using a linear combination of the subsystem wave-functions to represent the system wave-function we obtain a set of coupled equations for the expansion coefficients, by solving these energies and wave-functions can be obtained. We demonstrate the solution scheme with a standard model system: a confined harmonic oscillator in a one-dimensional box. With only a few (less than ten) basis functions from each subsystem, we can reproduce the exact solutions very accurately, thus showing the applicability of this method.     

Solving non-Markovian open quantum systems with multi-channel reservoir coupling

We extend the non-Markovian quantum state diffusion (QSD) equation to open quantum systems which exhibit multi-channel coupling to a harmonic oscillator reservoir. Open quantum systems which have multi-channel reservoir coupling are those in which canonical transformation of reservoir modes cannot reduce the number of reservoir operators appearing in the interaction Hamiltonian to one. We show that the non-Markovian QSD equation for multi-channel reservoir coupling can, in some cases, lead to an exact master equation which we derive. We then derive the exact master equation for the three-level system in a vee-type configuration which has multi-channel reservoir coupling and give the analytical solution. Finally, we examine the evolution of the three-level vee-type system with generalized Ornstein–Uhlenbeck reservoir correlations numerically.     

Stimulated Raman scattering in the approximation of unidirectional propagation in a medium with static dipole moments

The evolution equations of two-frequency stimulated Raman scattering in a molecular quasithree- level medium with static dipole moments have been derived in the approximations of the nondepletion of the pump field and the unidirectional propagation of the Stokes field. Completely integrable particular cases of the resulting system of equations have been found. New mechanisms of controlling the parameters of microwave pulses generated in such a system have been studied within this model. The numerical analysis and particular exact solutions demonstrate the possibility of switch between the regimes of generation of narrow Stokes field pulses and nearly rectangular pulses.     

Identification of overlapping optical lines in molecular spectra by means of the coherent population trapping of quantum levels

A new method of molecular beam spectroscopy with the ultrahigh resolution is theoretically suggested. This method is based on the phenomenon of the coherent population trapping of molecular levels and allows the identification of the overlapping optical lines in complex spectra (typical for polyatomic molecules), even when frequency intervals between the centers of given lines are less than their natural line widths. The theoretical analysis is carried out on the basis of the Schrödinger equation for the three-level molecular A-system interacting with the two-frequency laser radiation. The conditions of the practical realization and possible applications of the suggested spectroscopy method are discussed.