Kinetics of atoms in an elliptically polarized standing wave

We examine the kinetics of atoms with their ground and excited states being degenerate in the projection of angular momentum. The atoms are located in a standing wave with uniform elliptical polarization. Using the j _g =1/2→j _e =1/2 transition as an example, we show that the friction and diffusion of atoms strongly depend on the ellipticity of the field. For instance, in the low saturation limit the frictional force contains, in addition to the ordinary Doppler friction term, a term that can be interpreted as Sisyphean friction. Under certain conditions, the contributions reflecting the degeneracy of the ground state are dominant, with the result that the values of the friction and diffusion coefficients (and hence the rate of kinetic processes) may differ from the values predicted by the two-level atomic model by several orders of magnitude. Zh. éksp. Teor. Fiz. 115, 791–804 (March 1999)     

Basis of polarization-dressed states of an atom in an elliptically polarized resonant field

A basis of polarization-dressed states is proposed for atomic energy levels degenerate in the total angular momentum projections in the case of interaction with elliptically polarized light. It is shown that instead of selection rules for the magnetic quantum number, the interaction in this basis can be presented as the sum of direct transitions between corresponding pairs of polarization-dressed states of the upper and lower levels. The explicit form of the basis is derived for ten possible combinations of dipole transitions between energy levels with angular momenta J = 0, 1/2, 1, 3/2, and 2. The problem of Rabi oscillations in such a system is considered as an application.     

Features of magneto-optical resonances in an elliptically polarized traveling light wave

The parameters of nonlinear absorption magneto-optical resonances in the Hanle configuration have been studied as functions of the ellipticity of a traveling light wave. It has been found that these parameters (amplitude, width, and amplitude-to-width ratio) depend strongly on the polarization of the light wave. In particular, the resonance amplitude can increase by more than an order of magnitude when the polarization changes from linear to optimal elliptic. It has been shown that this effect is associated with the Doppler frequency shift for atoms in a gas. The theoretical results have been corroborated in experiments in Rb vapor.     

Shortened equations for the elliptically polarized wave

The field of an elliptically polarized wave is represented for the convenient solution of practical problems. The wave amplitude is written in terms of four parameters: magnitude E, phase φ, angle ψ of the polarization plane, and ellipticity ? (|?| is the ratio of the ellipse axes). The shortened equations are derived using these parameters and the solution of the shortened equations is obtained for a linear medium.     

Evolution of an intense elliptically polarized electromagnetic wave in underdense plasmas

An elliptically polarized electromagnetic wave in an underdense plasma acquires a longitudinal component of the electric field which oscillates as even harmonics of the fundamental frequency. The phase shift between transverse field components and the wave amplitudes exhibit nonlinear oscillations.     

Radioelectric effect in a superlattice under the action of an elliptically polarized electromagnetic wave

The density of the current associated with the drag of charge carriers in a superlattice by an elliptically polarized electromagnetic wave is calculated. Two cases of the mutual orientation of the Umov-Poynting vector and the superlattice axis, i.e., their parallel and perpendicular orientations, are analyzed. It is shown that, for the parallel orientation, the radioelectric effect can change sign. The influence of the longitudinal dc electric field on the radioelectric effect is investigated under the conditions where a circularly polarized electromagnetic wave propagates along the superlattice axis. The current density is studied as a function of the electric field strength and the electromagnetic wave intensity. It is demonstrated that the direction of the electric current is changed at specific values of the dc field strength and the wave intensity.     

Coherent trapping of a three-level atom in a circularly polarized light

Using semiclassical theory, we study coherent trapping of a three-level atom, where the atom possesses a momentum of its center-of-mass motion and is irradiated only by a classical circularly polarized electromagnetic wave. We find that if the atom is initially in a coherent trapping state of it, under the zero- or first-order approximation, the atom is absolutely or nearly in the state hereafter.     

A new representation of the interaction between an atom and an intense elliptically polarized electromagnetic field

A new representation of the interaction between a laser field and an atom is obtained. The Fourier component of the interaction is represented as a multipole expansion dependent on the force parameter of the field, a ₀=F/ω², and the degree of its ellipticity, η. This representation provides the analytical separation of the angles in the time-dependent Schrödinger equation. The stationary spherically symmetric part of the potential V ₀(r, a ₀, η) of a “field-dressed” atom is singled out. The application of the new representation to the calculation of nonlinear effects and electron scattering by an atom in a field are discussed     

Modulational instability of elliptically polarized transverse electromagnetic wave in a cold plasma

Modulational instability of an elliptically polarized transverse wave in a cold plasma is investigated by the use of Whitham's method of averaged Lagrangian including relativistic corrections. Instability condition and amplitude dependent frequency shift are derived.The authors wish to thank the referee for his valuable suggestion to improve the paper. The award of a Junior Research Fellowship to one of the authors (S.Sihi) by CSIR, India is gratefully acknowledged.     

Interaction of ultrashort elliptically polarized laser pulses with nonlinear helical photonic metamaterial

The effect of nonlinear properties of a material with a periodic structural cell (three-dimensional spiral) on the specificity of transmission and reflection of elliptically polarized laser pulses normally incident on the metamaterial is studied using the finite-difference time-domain method. An analysis of the hodograph of electric-field strength vector showed that an increase in the peak intensity of a linearly polarized laser pulse incident on a sample leads to an increase in the orthogonal component of the electric-field strength vector in the pulse transmitted through the medium. When pulses containing few electric-field periods are incident on a metamaterial, the latter demonstrates radically different optical properties for right- and left-handed circularly polarized light passing through the medium. It was shown that an increase in the intensity of a right-handed (left-handed) circularly polarized ultrashort pulse, incident on a sample composed of a rather large number of right-handed (left-handed) spirals made of nonlinearmaterial, widens the frequency range within which the incident light is almost entirely reflected from the medium.     

Extracting the phase distribution of the electron wave packet ionized by an elliptically polarized laser pulse

We use an interferometic scheme to extract the phase distribution of the electron wave packet from above-threshold ionization in elliptically polarized laser fields. In this scheme, an electron wave packet released from a circularly polarized laser pulse acts as a reference wave and interferes with the electron wave packet ionized by a time-delayed counter-rotating elliptically polarized laser field. The generated vortex-shaped interference pattern in the photoelectron momentum distribution enables us to extract the phase distribution of the electron wave packet in the elliptically polarized laser pulse with high precision. By artificially screening the ionic potential at different ranges when solving the time-dependent Schördinger equation, we find that the angle-dependent phase distribution of the electron wave packet in the elliptically polarized laser field shows an obvious angular shift as compared to the strong-field approximation, whose value is the same as the attoclock shift. We also show that the amplitude of the angle-dependent phase distribution is sensitive to the ellipticity of the laser pulse, providing an alternative way to precisely calibrate the laser ellipticity in the attoclock measurement.     

Attosecond temporal gating with elliptically polarized light

Temporal gating allows high accuracy time-resolved measurements of a broad range of ultrafast processes. By manipulating the interaction between an atom and an intense laser field, we extend gating into the nonlinear medium in which attosecond optical and electron pulses are generated. Our gate is an amplitude gate induced by ellipticity of the fundamental pulse. The gate modulates the spectrum of the high harmonic emission and we use the measured modulation to characterize the sub-laser-cycle dynamics of the recollision electron wave packet.     

Entanglement of a three-level trapped atom in the presence of another three-level trapped atom

A new version of two multi-level trapped atoms interacting with laser fields is under consideration. This system is based on a three-level trapped atom interacting with laser fields in the presence of another three-level trapped atom taking into account the time-dependent atom-field couplings and phase shift. The entanglement due to the concurrence is calculated and its time evolution phenomena is demonstrated within the framework of the presented theory. Our results establish an explicit relationship between the concurrence and the entanglement through the two three-level atoms and the fields interaction. We show that different nonclassical effects arise in the dynamics of the atomic population inversion, due to the initial states of the system as well as the values of the Lamb-Dicke parameter.     

Resonant fluorescence of a three-level atom

The fluorescence spectrum of a three-level atom interacting with strong electromagnetic monochromatic field is obtained. The calculations are based on the quantum “fluctuation-regression theorem”. It is shown, that the fluorescence spectrum contains five lines, the properties of which are discussed.     

三色圆偏振激光组合脉冲驱动氦原子产生椭圆偏振的阿秒脉冲

我们提出利用频率为ω,3ω和强度较弱的2ω组成的三色圆偏振激光组合脉冲驱动氦原子能够得到椭偏率较大的阿秒脉冲链的一种方法.通过强场近似方法,计算了氦原子在两色和三色圆偏振激光组合脉冲驱动下发射高次谐波谱及其合成阿秒脉冲链,比较了氦原子(初态为s态)在这两种情况下发射高次谐波谱的特点及其合成阿秒脉冲链椭偏率的大小,结果发现,在反旋的两色ω,3ω激光脉冲基础上加入了频率为2ω的第三色激光脉冲联合作用到氦原子上,所得到的阿秒脉冲链的椭偏率相对于双圆场情况下有所增加,通过调整ω,3ω激光的强度比,并且选择适当的第三色激光的强度,对初态为s态的原子,仍能够得到具有较大椭偏率的阿秒脉冲链.     

Nonlinear reflection of elliptically polarized light

Nonlinear reflection of elliptically polarized light waves from the interface of two isotropic transparent media, is investigated for the first time. Nonlinear Fresnel formulae are obtained. It is shown, that when linear refractive indices are equalized, selfdeformation of the polarization ellipse in nonlinear reflection depends only on incident light ellipticity, not upon its intensity and the angle of incidence.     

关于椭圆偏振光与圆偏振光的实验验证

讨论了椭圆偏振光与圆偏振光的实验验证,从理论和实验两方面指出并分析了目前存在的一些问题．     

Dynamics of a tri-beam laser interacting with a three-level atom

We investigate the dynamics of a tri-beam laser interacting with a closed three-level atomic system. The Bloch equations are obtained using Hesinberg??s equation of motion. The impact of the resulting parameters on the atomic occupation probabilities and information entropy is discussed. It is shown that the populations are affected by the detuning in different ways which are then compared in order to simulate realizations entanglement through the information entropy.