Quantum phases for a generalized harmonic oscillator

An effective Hamiltonian for the generalized harmonic oscillator is determined by using squeezed state wavefunctions. The equations of motion over an extended phase space are determined and then solved perturbatively for a specific choice of the oscillator parameters. These results are used to calculate the dynamic and geometric phases for the generalized oscillator with this choice of parameters.      

Theoretical investigation of amplitudes and phases in exciton reflection spectra

The phase difference Δ between the p and s component of light reflected from a semiconductor in the spectral region of the 1-S exciton is theoretically investigated. The exciton polariton theory used leads to a very good agreement with experimental spectra. No additional assumptions, such as ABC (additional boundary condition) or dead layer are necessary.     

All-optical measurement of high-harmonic amplitudes and phases in aligned molecules

We report a new all-optical approach to measuring the phase and amplitude of high-harmonic emission from aligned molecules. We combine the transient grating technique with a continuous rotation of the molecular alignment axis and develop an analytical model that enables the simultaneous determination of phases and amplitudes. Measurements in N(2) molecules are shown to be in qualitative agreement with the results of ab initio quantum scattering calculations.     

Dual amplitudes of baryonium interaction

It is shown that the interaction of the M₀^J-baryonium can be described by Brower-Goddard dual amplitudes with n=3, where n is the dimension of “Koba-Nielsen” variables.     

Casimir amplitudes in a quantum spherical model with long-range interaction

A d-dimensional quantum model system confined to a general hypercubical geometry with linear spatial size L and “temporal size” 1/T ( T - temperature of the system) is considered in the spherical approximation under periodic boundary conditions. For a film geometry in different space dimensions , where is a parameter controlling the decay of the long-range interaction, the free energy and the Casimir amplitudes are given. We have proven that, if , the Casimir amplitude of the model, characterizing the leading temperature corrections to its ground state, is . The last implies that the universal constant of the model remains the same for both short, as well as long-range interactions, if one takes the normalization factor for the Gaussian model to be such that . This is a generalization to the case of long-range interaction of the well-known result due to Sachdev. That constant differs from the corresponding one characterizing the leading finite-size corrections at zero temperature which for is . Received 3 June 1999 and Received in final form 16 August 1999     

Unitarity bounds for multiparticle interaction amplitudes

A regular method of asymptotical estimations for multiparticle interaction amplitudes is constructed. The method gives a generalization of the well-known Froissart result to the multiparticle case.     

交替寻优生成元素幅值结合混沌随机相位构造循环测量矩阵

循环矩阵由于其对应离散卷积且具有快速算法被广泛应用于压缩测量矩阵. 本文从循环测量矩阵生成元素的幅值和相位两个方面探索循环测量矩阵的优化构造, 提出交替寻优生成元素的幅值并结合混沌随机相位实现循环测量矩阵的最优构造. 由一维和二维信号循环测量矩阵的不同表示形式出发, 将等价字典列向量之间互相干系数的Welch界作为逼近目标, 推导出了一维和二维信号循环测量矩阵生成元素幅值优化的统一数学模型, 提出采用交替寻优方法求解生成元素幅值的最优解. 利用混沌序列构造循环测量矩阵生成元素的随机相位. 与已有的典型循环测量矩阵相比, 本文优化构造的循环测量矩阵所对应的等价字典列向量之间具有更低的互相干性, 这正是所构造的循环测量矩阵优越性的本质所在.     

Measurement of phases and amplitudes of AWG by fitting interference intensities

We measured the phases and amplitudes of an arrayed waveguide grating (AWG) by fitting interference intensities via a frequency domain method. The intensities were recorded as a function of the laser frequency in an interferometer containing the AWG. We fit the theoretical intensity profile to the recorded data via the Monte-Carlo method after filtering out the low-frequency noise. The phases and amplitudes are the parameters in the fitting process, and hence, the values are determined from the final fit. The variations in the measured phase values with the change in the initial condition of the Monte-Carlo process were less than $0.1^\circ $ . The variations in the measured amplitude values were negligible. In order to verify our measurement, we calculated the transmission spectrum of the AWG using the measured phases and amplitudes and compared it with a directly measured spectrum. The calculated and measured spectrums are in good agreement with each other.     

q-Anharmonic oscillator with quartic interaction

The first order perturbative correction to the energy levels of a boson realization of aq-oscillator due to a quartic term in the potential energy is evaluated. We also discuss the statistical mechanics ofq-anharmonic oscillators in the case where the parameterq deviates slightly from unity.     

扩展互作用谐振腔的模拟分析

 分析了扩展互作用谐振腔的工作原理、特点以及工作过程,并利用PIC粒子模拟程序对其进行了数值模拟,分析了阴极电压、电子注半径、谐振腔个数以及谐振腔周期长度对输出功率、频率及转换效率的影响。结果表明：当阴极电压为28.5~30.0 kV时,谐振腔能正常工作;当电子注半径为1.4 mm,谐振腔个数为4,阴极电压为29 kV时输出功率和转换效率最大,输出功率为128 kW,频率12.9 GHz,转换效率达37.93%;输出频率随谐振腔周期长度的变小而增大。     

扩展互作用谐振腔的模拟分析

分析了扩展互作用谐振腔的工作原理、特点以及工作过程,并利用PIC粒子模拟程序对其进行了数值模拟,分析了阴极电压、电子注半径、谐振腔个数以及谐振腔周期长度对输出功率、频率及转换效率的影响。结果表明：当阴极电压为28.5~30.0 kV时,谐振腔能正常工作;当电子注半径为1.4 mm,谐振腔个数为4,阴极电压为29 kV时输出功率和转换效率最大,输出功率为128 kW,频率12.9 GHz,转换效率达37.93%;输出频率随谐振腔周期长度的变小而增大。     

波瓣波导谐振腔太赫兹回旋管的研究

以电子回旋脉塞非线性理论为基础, 结合三维电磁仿真软件, 通过导入高频场数值解替代理论解析的方法, 对波瓣波导谐振腔高次谐波太赫兹回旋管进行了理论和模拟研究. 给出了该类回旋管的起振电流、耦合系数以及注波互作用效率等重要参数, 并在此基础上设计了一只工作频率为0.4 THz, 工作模式TE₃₃模三次谐波波瓣波导谐振腔回旋管, 其电子注参数为1.0 A, 40.5 kV, 横纵速度比1.5,互作用区引导磁场为5.09 T, 输出功率达到3.3 kW.     

An extended interaction oscillator based on a complex resonatorstructure

We report experimental investigation of a novel scheme for efficient interaction between a linear electron beam and an electromagnetic wave in a complex extended interaction structure. The structure of interest consists of a high R/Q, five-gap, coupled-cavity resonator that incorporates a coaxial section of a quarter plasma wavelength placed between the first and second cavities. In the coaxial section, beam and wave propagate in separate channels. The first cavity, strongly coupled to the other cavities through the wave channel of the coaxial section, serves as a buncher cavity. An inner channel running through the center conductor of the coaxial section provides a cutoff drift space for ballistic bunching of electrons, an effect that is shown to significantly enhance the interaction efficiency. Oscillation power of 2.2 kW at 16.6 GHz was demonstrated with an interaction efficiency of 30%. The total efficiency was further increased to 41% by incorporation of a two-stage depressed collector     

Investigation of a mutual interaction force at different pressure amplitudes in sulfuric acid

This paper investigates the secondary Bjerknes force for two oscillating bubbles in various pressure amplitudes in a concentration of 95% sulfuric acid.The equilibrium radii of the bubbles are assumed to be smaller than 10 μm at a frequency of 37 kHz in various strong driving acoustical fields around 2.0 bars (1 bar=10 5 Pa).The secondary Bjerknes force is investigated in uncoupled and coupled states between the bubbles,with regard to the quasi-adiabatic model for the bubble interior.It finds that the value of the secondary Bjerknes force depends on the driven pressure of sulfuric acid and its amount would be increased by liquid pressure amplitude enhancement.The results show that the repulsion area of the interaction force would be increased by increasing the driven pressure because of nonlinear oscillation of bubbles.     

Baryon-baryon and baryon-antibaryon interaction amplitudes in the spin-momentum operator expansion method

Partial-wave scattering amplitudes in baryon-baryon and baryon-antibaryon collisions and amplitudes for the production and decay of baryon resonances are constructed in the framework of the spin-momentum operator expansion method. The approach is relativistically invariant and it allows us to perform combined analyses of different reactions imposing analyticity and unitarity directly. The role of final-state interactions (triangle and box diagrams) is discussed.     

Mode interaction in a spatially inhomogeneous laser

In this paper the influence of spatial matter inhomogeneities on laser action is investigated theoretically. The calculations are based on nonlinear laser theory for the amplitudes of the empty-cavity modes. The nonlinear mode interactions like mode suppression or phase locking are modified by spatial inhomogeneities. There also arises a linear coupling among the cavity modes in general leading to monochromatically oscillating states which are superpositions of the empty-cavity eigenfunctions.     

The interaction of resonances in a weakly nonlinear oscillator with a quasiperiodic excitation

Conditions for chaos onset due to the interaction of resonances in a weakly nonlinear oscillator with a quasiperiodic excitation are investigated. The focus is made on the interaction of the 1:1 resonance with that of 1:m, where m is an arbitrary integer number. Analytical conditions of the chaos arising are obtained through the combined application of the averaging procedure and Melnikov's technique. The comparison study of these conditions with those following from standard Chirikov's approach is provided. (c) 1997 American Institute of Physics.