二项式光场与级联三能级原子在非旋波近似下相互作用的量子特性

利用全量子理论,在非旋波近似下,对与级联型三能级原子相互作用的二项式光场的光场压缩效应和原子布居几率进行了精确求解.讨论了二项式光场参量η对光场压缩效应的影响,同时也讨论了二项式态光场的最大光子数M对原子布居几率的影响.数值计算结果表明:随着二项式光场参量η的增大,光场压缩效应的持续时间先增大后减小.在非旋波近似下,由于虚光子的影响,光场压缩效应的演化曲线出现了"小锯齿状"的振荡;随着二项式光场的最大光子数M的增大,原子布居几率回复塌缩周期逐渐增大,并且原子布居几率在塌缩区不能完全塌缩,而是出现了"小锯齿状"的振荡.另外文中也讨论了非旋波项对系统量子特性的影响.     

二项式光场与级联三能级原子在非旋波近似下相互作用的量子特性

利用全量子理论,在非旋波近似下,对与级联型三能级原子相互作用的二项式光场的光场压缩效应和原子布居几率进行了精确求解.讨论了二项式光场参量η对光场压缩效应的影响,同时也讨论了二项式态光场的最大光子数M对原子布居几率的影响.数值计算结果表明:随着二项式光场参量η的增大,光场压缩效应的持续时间先增大后减小.在非旋波近似下,由于虚光子的影响,光场压缩效应的演化曲线出现了“小锯齿状”的振荡;随着二项式光场的最大光子数M的增大,原子布居几率回复塌缩周期逐渐增大,并且原子布居几率在塌缩区不能完全塌缩,而是出现了“小锯齿状”的振荡.另外文中也讨论了非旋波项对系统量子特性的影响.     

椭圆高斯光束产生近似无衍射Bessel-Gauss光

研究了轴棱锥聚焦像散椭圆高斯光束的光场分布特性,根据菲涅耳衍射积分理论导出了椭圆高斯光束经轴棱锥衍射后的光场分布,通过数值积分给出椭圆高斯光束经轴棱锥聚焦后的近轴光场强度分布情况,将其与圆高斯光束产生的近似Bessel-Gauss场进行比较,发现椭圆高斯光束经轴棱锥聚焦后的光束在一定的传播距离内也具有无衍射特性,且轴上光强分布与圆高斯光束产生的Bessel-Gauss光束的轴上光强分布具有相似的形式,而这种无衍射光场的强度在垂直于光轴的平面上不再是柱对称分布。根据近轴球面波产生近似Bessel光束的最大无衍射距离公式计算了椭圆Bessel-Gauss光束在子午面和弧矢面上的最大无衍射距离,整个光束的无衍射距离由入射到轴棱锥上的椭圆光斑短轴方向的尺寸决定。     

非旋波近似下光场与V型三能级原子依赖强度耦合作用系统中的光场压缩

利用全量子理论,研究了非旋波近似下单模光场与V型三能级原子依赖强度耦合的相互作用系统中光场的压缩效应.结果表明:光场的压缩依赖于系统的本身性质,而虚光子过程使光场的压缩程度明显加强并产生量子噪声,其大小依赖于初始场平均光子数n和光场频率ω,且与原子光场耦合强度g有关.     

随机表面散射光场的格林函数法与基尔霍夫近似的比较

从简谐光波满足的亥姆霍兹方程出发，将由格林定理得到的介质分界面上的积分方程转化为以表面上的光波及其导数为未知量的线性方程组，并对其进行数值求解，实现了光场的数值计算. 同时，由透射光场的格林函数积分得出了基尔霍夫近似下光场的表达式. 通过类比推导夫琅和费面上散斑场自相关函数的方法，提出了产生随机表面及其导数的傅里叶变换方法. 在此基础上，对采用基尔霍夫近似进行自仿射分形随机表面的散射光场数值计算的精确程度进行了研究. 发现在随机表面粗糙度比较小时，基尔霍夫近似的精度比较高；在粗糙度相同的情况下，表面的分形 关键词： 格林函数积分 基尔霍夫近似 自仿射分形随机表面     

非旋波近似下频率变化的场与原子的相互作用

研究了非旋波近似下频率随时间变化的相干态光场与二能级原子的相互作用，主要讨论了光场频率随时间作正弦和方波变化两种典型情况下，原子布居数反转随时间的演化特性. 当光场频率随时间作正弦变化时，原子布居数反转的崩塌-回复过程和由虚光子过程引起的快速振荡均会受到影响. 当光场频率随时间以方波形式变化时，脉冲调制不仅在原子布居数反转随时间演化过程中诱导出新的崩塌-回复过程，而且可以引起虚光子快速振荡的突变. 关键词： Jaynes-Cummings模型 非旋波近似 原子布居数反转     

非旋波近似下二项式光场与V型三能级原子相互作用的量子特性

采用相干态正交化展开方法,研究了非旋波近似下V型三能级原子与单模腔场的相互作用,并且利用保真度对能级的交叉问题进行了判断.研究了在二项式光场作用下,V型三能级原子初始状态以及二项式态光场的光场系数对光场二阶相干度的影响.数值计算结果表明:原子初始时刻处于基态时,随着η的增大光场呈现聚束效应的持续时间先增大后减小;原子初...     

非旋波近似下压缩真空场与三能级原子依赖强度耦合系统的光场压缩

利用全量子理论,研究了非旋波近似下压缩真空场与V型三能级原子依赖强度耦合相互作用系统中光场的压缩效应.数值计算结果表明:光场呈现出周期性压缩现象,而虚光子过程则对光场的压缩具有抑制作用并产生量子噪声,量子噪声大小依赖于光场的初始压缩因子r和光场频率ω,且与原子-光场耦合强度g有关.随着r的增大,虚光子过程对光场压缩抑制作用程度由弱到强再由强到弱;随着ω和g的增大,量子噪声分别减小和增大.     

非旋波近似下两个二能级原子与单模光场相互作用的非经典性质

利用全量子理论,研究了非旋波近似下两个二能级原子与单模光场相互作用过程中光场所表现出的非经典性质,揭示了虚光子过程对场的平均光子数和二阶相干度的影响,并讨论了光场频率及原子间耦合系数的变化与场的平均光子数和二阶相干度的关系.     

薛定谔猫态光场与二能级原子相互作用系统的量子特性

在非旋波近似下,通过采用相干态正交化展开的方法,研究了薛定谔猫态光场与二能级原子相互作用系统中,原子的布局数和光场的反聚束效应,并与旋波近似下的结果进行了对比.在旋波近似与非旋波近似下,讨论了初始光场强度、相干态间的相位角以及失谐量对原子布局数和光场反聚束效应的影响;在非旋波近似下,讨论了强弱耦合情况下光场的反聚束效应.研究结果表明:旋波近似与非旋波近似下,原子的布局数随着初始光场强度的不同,表现出不同的特性;当初始光场强度较小时,旋波近似与非旋波近似下,原子的布局数表现出相同的特性;随着初始光场强度的增大,旋波近似下,原子的布局数将表现出坍塌现象.耦合强度较大时,光场的聚束与反聚束效应在非旋波近似与旋波近似下有较大的区别;非旋波近似下,随着初始光场强度的增大,光场一直处于聚束效应状态;而旋波近似下,光场的聚束效应与反聚束效应交替出现.     

Radiation of scalar waves by the discontinuities in the antenna geometries

The electrical scalar potential satisfies the Helmholtz equation for time-harmonic waves and Aharonov-Bohm showed that the electromagnetic potentials have physical reality. For these reasons, the scalar potential represents scalar wave propagation in space. The gradient of the scalar wave leads to the electric field intensity, but it does not create the magnetic field. The criteria for the radiation of the scalar waves are studied on various linear antennas. The radiation integrals of the antennas are evaluated asymptotically by taking into account the edge effects. The radiation diagrams are plotted numerically and the phase velocities of the scalar waves are investigated in the near field.     

Coherent control of spontaneous emission and radiation property in an anisotropic PBG

The spontaneous emission and radiation properties of a three-level atom driven by a phase-sensitive laser field in the anisotropic photonic crystal have been investigated. Due to the modified density in PC and the dynamical coherence induced by the coupling field, the population becomes oscillated and a fractionalized steady-state inversion appears in the two upper levels under certain initial conditions. And the spontaneous spectra are influenced not only by the photonic band edge but also by the phase and the detuning of the coherent field. In addition, the phase dependent quantum interference leads to fluorescence quenching and enhancement in the spectra. Meanwhile, the radiation fields are greatly dependent on the intensity of the coherent field and the relative position of the resonant frequency to the band edge. Different kinds of fields within the regions we plotted are clearly calculated. When the resonant frequency moves from deep in the band gap to the band, localized field, diffusion field and propagating field regularly vary and the energy of them is exchanged to each other.     

Analysis of the amplitude and phase structure of transmitting media with probing field registration in the image plane

The problem of obtaining information on the amplitude and phase internal structure of a medium in which radiation propagates is considered. The information is extracted by probing the medium; the information on the amplitude and phase distribution of the probing field behind the transmitting medium in the plane of image formation is analyzed. A modified version of the modulation-spectral method proposed earlier by the authors is applied. In this version, there is no need to act on the probing field in the plane under investigation. The interpretation of results is simplified since the image is registered. Two versions of the schematic solution are analyzed. The first version corresponds to the experimental scheme intended for media that produce a modulating action on radiation and is described by multiplication by a complex function characterizing the action. The second version corresponds to the case when the action of the medium leads to a redistribution of radiation and can be presented by the convolution of the probing signal and the function describing the action.     

Effect of the anode-current magnetic field on the motion of electrons in a triode with a virtual cathode

The effect of the anode-current magnetic field on the electron motion in a triode with a virtual cathode is considered. It is shown that the anode-current magnetic field influences the oscillation period and trajectories of electrons. The condition of self-isolation of the electron beam is investigated as a function of the diode parameter. It is shown that the displacement of the beam electrons under the action of the anode-current magnetic field leads to a decrease in the electron phase modulation and an increase in the spread in the electron oscillation amplitude; as a result, the generation efficiency of microwave radiation decreases.     

Quantum electrodynamic fluctuations of the macroscopic Josephson phase

We study the equilibrium dynamics of the relative phase in a superconducting Josephson link taking into account the quantum fluctuations of the electromagnetic vacuum. The photons act as a superohmic heat bath on the relative Cooper pair number and thus, indirectly, on the macroscopic phase difference φ. This leads to an enhancement of the mean square 〈φ²〉 that adds to the spread due to the Coulomb interaction carried by the longitudinal electromagnetic field. We also include the interaction with the electronic degrees of freedom due to quasiparticle tunneling, which couple to the phase and only indirectly to the particle number. The simultaneous inclusion of both the radiation field fluctuations and quasiparticle tunneling leads to a novel type of particle-bath Hamiltonian in which the quantum particle couples through its position and momentum to two independent bosonic heat baths. We study the interplay between the two mechanisms in the present context and find interference contributions to the quantum fluctuations of the phase. We explore the observability of the QED effects discussed here.     

Influence of dissipation on phase tunneling in Josephson-junctions

The coupling between the phase and the electromagnetic field in the case of a tunnel junction is treated by Feynmans path integral method. It is shown that the elimination of the field leads to a frequency dependent mass for the motion of the phase , which is simply related to the effective dielectric constant of the junction. Considering tunneling as a motion in imaginary time one obtains a polaron like mass enhancement connected to the dielectric function at positive imaginary frequencies, which essentially leads to the Caldeira-Leggett reduction of the elastic tunneling probability. In the weak damping limit it is shown that the emission of real excitations during tunneling is a higher order effect. At low temperatures the damping finally is determined by the linewidth of electromagnetic radiation at the Josephson plasma frequency.     

Envelope,phase, and frequency of ultrabroadband signal in a transparent medium

Analytical signal formalism is used for derivation of expressions for a complex envelope of radiation with ultrabroadband spectrum and an arbitrary waveform, which occur rarely in modern texts on nonlinear optics. It is demonstrated that the envelope, phase, and instantaneous frequency of femtosecond radiation pulses with an ultrabroad spectrum in a transparent medium can exhibit oscillations with a characteristic time scale considerably shorter than one field cycle at the central frequency. The interference of pulses and the generation of multiple frequencies are among phenomena giving rise to such features. It is marked that the violation of conditions imposed by the theory of analytical signal leads to ambiguity of the complex envelope.     

Modulation-spectral method for analyzing the amplitude-phase structure of optical inhomogeneities of objects

An original solution to the phase problem in optics is considered as applied to the problems of recording and analysis of the amplitude-phase structure of optical fields used for studying fine structures and inhomogeneities in steady-state objects producing effects to fractions of the wavelength period. The problem is solved by probing objects using radiation with a known structure. Intensity distributions of the probing field are detected at the exit from the object by using the modulation-spectral method directly for the spatial frequency spectrum and for the spatial frequency spectrum subjected to additional modulation formed in a special way, which is realized in the plane under study and provides visualization of the phase information contained in the light field in some form. The intensity distributions obtained make it possible to calculate the two-dimensional amplitude-phase structure of the field analyzed and, hence, the fine structure of the optical inhomogeneities of the object analyzed for the chosen probing direction. For steady-state objects, probing in a number of directions is possible. Information on the bulk structure of the inhomogeneities under study can be obtained by using the information available on the symmetry of the object. Two variants of action of the medium on probing radiation are considered. In the first one, the action is related to spatial field modulation (described by the multiplication operation); in the second one, the action leads to redistribution of radiation in the plane studied (described by the convolution operation).     

空场诱导相干性对倒转Y型四能级原子系统中单光子和双光子吸收性质的影响

当倒转Y-型四能级原子的两基态能级邻近简并时,连接基态的两个跃迁路径与同一个真空场辐射场相互作用导致的量子干涉效应便产生了空场诱导相干性.空场诱导相干性能使倒转Y-型四能级原子在共振点的单光子和双光子电磁诱导透明现象减弱,而在其他失谐量处产生单光子增益现象。同时,外加相干光场的相对相位对原子的吸收性质有重要的影响.