基于标度理论求解两分量玻色-爱因斯坦凝聚集体激发模

文章基于标度理论研究了两分量玻色-爱因斯坦凝聚的集体激发模。首先从耦合流体力学方程组出发,对两分量玻色-爱因斯坦凝聚的粒子数密度和速度场分别采用相应的标度假设,为了满足在不同分量相互作用下的标度假设,需在全空间做平均,最后得到柱对称下两分量玻色-爱因斯坦凝聚集体激发模的色散关系。

激发双模压缩真空态的非经典特性

通过数值计算研究了激发双模压缩真空态 a+ mb+ m|ξ〉的非经典特性 .结果表明 :对于a+ mb+ m | ξ〉,Cauchy-Schwartz不等式受到破坏 ;当取适当的压缩参量 r(例如 0 .4～ 0 .7)时 ,a+ mb+ m| ξ〉呈现出正交分量的压缩和光子的亚泊松分布 ,而且压缩程度和亚泊松特性都随 m的增大而有所增强 .

叠加激发双模压缩真空态的量子统计特性(英文)

从激发双模压缩真空态 a mb m| ξ〉出发构造了叠加态 | Ψ〉,研究了 | Ψ〉的量子统计特性 .结果表明 :在一定的条件下 ,随着相位差的变化 ,叠加态 | Ψ〉的平均光子数出现类似于Rabi振荡的崩塌与复原现象 ,而且与单个激发双模压缩真空态 a mb m|ξ〉相比 ,在叠加态

叠加激发双模SU(2)相干态的量子统计特性

构造了叠加激发双模SU(2)相干态|ψ>=Cm(|M,;ξm>+ei|M,ξ*;m>),用数值方法研究它的量子统计特性。结果表明:叠加激发双模SU(2)相干态两场模的光子统计分布保持反关联特征,而且呈现奇特的光放大特性;b模光场的亚泊松分布得到比较大的加强,而a模光场的亚泊松分布特性则有轻微减弱;两场模的反聚束性均得到增强;随激发量子数m的增大,两场模间的反关联性减弱。

激发双模SU(2)相干态的非线性高阶差压缩

通过数值计算方法,研究了激发双模S(U 2)相干态M,!;m〉=AM!ma+mb+m M,!〉的非线性高阶差压缩——N次方X压缩效应。结果表明:对于激发双模SU(2)相干态,光场存在着非线性高阶差压缩(即(N=1,2,3,4,5…)次方X压缩)效应,且随着光场总光子数M的增加,N次方X压缩效应增强,但增大场模光子增加数m或增大N次方X压缩的压缩阶数N,N次方X压缩效应减弱。

激发双模压缩真空态的等阶Y压缩效应

本文研究了激发双模压缩真空态a+mb+m|ξ〉的等阶Y压缩效应。数值计算的结果表明:对于态a+mb+m|ξ〉,光场存在着等阶K(=2,3,4,5,…)次方Y压缩效应,而且随着场模上光子增加数m的增大,等阶K次方Y压缩效应增强。

OCS^+经由A^2П←X^2П激发的光解离光谱

在超声分子束条件下,由423、420、412.2和408.4nm的电离激光使OCS分子通过[3+1]共振增强多光子电离(REMPI)制备出OCS+(X2Π)离子后,在260-325nm范围内扫描解离激光获得了OCS+离子经由A2Π3/2←X2Π3/2(000)和A2Π1/2←X2Π1/2(000,001)跃迁的分质量光解离谱(母体离子OCS+的凹陷谱和碎片离子S+的增强谱).其中A2Π1/2←X2Π1/2(001)跃迁的光解离谱是首次观察到.由A2Π3/2←X2Π3/2(000)光解离谱得到了A2Π3/2电子态的光谱常数T0=31411.3cm-1,ν1=814.3cm-1;由A2Π1/2←X2Π1/2(000)光解离谱得到了A2Π1/2电子态的光谱常数ν1=816cm-1,ν2=(380.4±2.8)cm-1,ν3=(2052.7±5.1)cm-1,而从A2Π1/2←X2Π1/2(001)光解离谱拟合出的A2Π1/2电子态的ν1(786.4cm-1)稍有不同,表明在A2Π1/2←X2Π1/2(001)跃迁中X2П1/2电子态的C-O键振动(ν3)激发影响了A2Π1/2电子态C-S键的振动(ν1).实验结果表明:在A2Π1/2←X2Π1/2(000,001)跃迁的光解离谱中能够显著观察到属于A2Π电子态的ν2弯曲振动模激发的谱峰,例如A2Π1/2(020,120,021,…),而在A2П3/2(υ1υ2υ3)←X2Π3/2(000)跃迁的光解离谱中几乎没有观察到属于ν2弯曲振动模激发的谱峰.这种弯曲振动激发和A2П电子态的旋轨分裂分量(Ω)的相关性可以通过A2Π电子态的Fermi共振和Renner-Teller效应来解释.

Optically Activated Charge Domain Model for High-Gain GaAs Photoconductive Switches

A model for theoretical analysis of nonlinear (or high gain) mode of photoconductive semiconductor switches (PCSS's) is proposed.The switching transition of high gain PCSS's can be described with an optically activated charge domain. The switching characteristics including rise time,delay and their relationship to electric field strength,optical trigger energies are discussed.The formation and radiation transit,accumulation of the charge domain are related with the triggering and sustaining phases of PCSS's,respectively.The results of the mathematical model on this mechanism agree with experimental results.

The analysis on IP signals in TEM response based on SVD

During transient electromagnetic method （TEM） exploration of a copper mine, we detected the late-channel TEM signal reversal phenomenon （a voltage change from positive to negative） caused by the influence of the induced polarization （IP） effect, which affects the depth and precision of the TEM detection. The conventional inversion method is inefficient because it is difficult to process the data. In this paper, the Cole-Cole model is adopted to analyze the effect of Dc resistivity, chargeability, time constant, and frequency exponent on the TEM response in an homogeneous half space model. Singular Value Decomposition （SVD） is used to invert the measured TEM data, and the Dc resistivity, chargeability, time constant and frequency exponent were extracted from the measured TEM data in the mine area. The extracted parameters are used for interpreting the detection result as a supplement. This reveals why the TEM data acquired in the area has a low resolution. It was found that the DC resistivity and time constant do not significantly change the results, however, the chargeability and frequency exponent have a significant effect. Because of these influences, the SVD method is more accurate than the conventional method in the apparent resistivity profile. The area of the copper mine is confined accurately based on the SVD inverted data. The conclusion has been verified by drill and is identical to the practical geological situation.

对应负二项式光场的热真空态及其应用

有限温度下的光场理论的核心是引入热真空态,它也是利用量子统计手段全面研究电磁场的基础.本文在Takahashi和Umezawa的热场动力学理论基础上,首次采用有序算符内的积分方法对负二项式光场ρs=∞∑n=0(n+s n)γs+1(1-γ)n|n><n|,寻找相应的热真空态.发现该热真空态是基于在混沌光场所对应的热真空态上的虚模激发,或取负二项式纯态的形式∞∑n=0(n+s n)γs+1(1-γ)n|n,s+>,其中"s"代表虚模自由度.对此热真空态求纯态平均可方便地得到负二项式光场的Wigner函数和光子数涨落.

Functional Integrals and Collective Excitations in Boson-Fermion Model

In this paper, collective excitations in the boson-fermion model are investigated by means of functional integration method. The equations of energy gap and excitation spectrum are derived. Moreover, the Bose energy spectrum of zero wave vector Fermi fields is also calculated.

Cellular Automaton Simulations for Target Waves in Excitable Media

Using the Greenberg-Hasting cellular automata model, we study the properties of target waves in excitable media under the no-flux boundary conditions. For the system has only one excited state, the computer simulation and analysis lead to the conclusions that, the number of refractory states does not influence the wave-front speed; the wave- front speed decreases as the excitation threshold increases and increases as the neighbor radius increases; the period of target waves is equal to the number of cell states; the excitation condition for target waves is that the wave-front speed must be bigger than half of the neighbor radius.

Impact of substrate on opto-thermal response of thin metallic targets under irradiation with femtosecond laser pulses

Femtosecond pulsed lasers have been widely used over the past decades due to their capability to fabricate precise patterns at the micro-and nano-lengths scales. A key issue for efficient material processing is the determination of the laser parameters used in the experimental set ups. Despite a systematic investigation that has been performed to highlight the impact of every parameter independently, little attention has been drawn on the role of the substrate material on which the irradiated solid is placed. In this work, the influence of the substrate is emphasised for films of various thicknesses, which demonstrates that both the optical and thermophysical properties of the substrate affect the thermal fingerprint on the irradiated film while the impact is manifested to be higher at smaller film sizes. Two representative materials, silicon and fused silica, have been selected as typical substrates for thin films(gold and nickel) of different optical and thermophysical behaviour and the thermal response and damage thresholds are evaluated for the irradiated solids. The pronounced influence of the substrate is aimed to pave the way for new and more optimised designs of laserbased fabrication set ups and processing schemes.

Nucleon—Pair Shell Model：Magnetic Excitations for Ba Isotopes

Magnetic excitations for Ba isotopes are discussed within the nucleon-pair shell model truncated in the SD subspace. With the SD pair determined by a surface- interaction, M1 transitions for are well fitted. The M1 and M3 transitions for and are also predicted. It is shown that the statement, the collective magnetic properties are due to the orbital motion of nucleons, is approximately valid.

Test study on rupture process and permeability properties of coal-rock in simulating mining stress effect

A test system was designed by using a set of self-made experimental devicesof coupled coal-gas in simulating mining stress effect, combining the equipment withRMT-150B rock mechanical experimental system, monitoring the rupture process ofcoal-rock with an acoustic emission (AE) device and collecting gas-flow rate andgas-stress data in real-time automatically with a gas flow-meter and gas pressure sensor.The fracture process and permeability properties test of the coal-rock in mining stress effect was carried out. Test results indicate that AE events and variation of stresses have thesame variance tendency and the rupture process of coal-rock can be monitored by AE.The relation curves among stresses, parameters of AE and permeability properties demonstrate that the permeability of coal-rock decreases gradually at quasi-elastic stage, increases gradually at plastic damage micro-fracture stage, rises suddenly near the peakpoint and has multi-variation at post-peak slip stage. From the results, such conclusioncan be drawn that the variation of permeability can be monitored by AE parameters orstress change.

Understanding Rotational Mode Specificity in the O（3P）+CHD3→OH+CD3 Reaction by Simple Reactant Alignment Pictures

The mode specificity plays an important role in understanding the fundamental reaction dynamics. This work reports a theoretical study of the rotational mode specificity of the reactant CHD3(JK) in the prototypical hydrocarbon oxidation reaction O(3P)+CHD3→OH+CD3. The time-dependent quantum wave packet method combined with a seven-dimensional reduced model is employed to calculate the reaction probability on an accurate potential energy surface. The obtained reaction probability depends on the values of both K and Ktot with PKtot=K=0>PKtot=K=J>PKtot=J,K=0=PKtot=0,K=J. This observation can be well rationalized by the reactant alignment pictures. Rotational excitations of CHD3 up to the angular momentum quantum number J=4 have a very weak enhancement effect on the reaction except for the state (J=4, K=0). In addition, the rotationally excited states of CHD3 with K=0 promote the reaction more than those with K=J. The quantum dynamics calculations indicate that the K=0 enhancements are mainly caused by the contributions from the components with K=Ktot=0. The components correspond to the tumbling rotation of CHD3, which enlarges the range of the reactive initial attack angles.

Nonclassical Effects of a Four-Level Excited-Doublet Atom Model

We adopt a dynamical algebraic method to study a four-level excited-doublet atom model and obtain the explicit expressions of the time-evolution operator and the density operator for the system. The nonclassical effects of the system, such as collapses and revivals of the atomic inversion and squeezing of the radiation field, are also discussed.

Dynamic failure mode and energy-based identification method for a counter-bedding rock slope with weak intercalated layers

The dynamic failure mode and energybased identification method for a counter-bedding rock slope with weak intercalated layers are discussed in this paper using large scale shaking table test and the Hilbert-Huang Transform(HHT) marginal spectrum.The results show that variations in the peak values of marginal spectra can clearly indicate the process of dynamic damage development inside the model slope.The identification results of marginal spectra closely coincide with the monitoring results of slope face displacement in the test.When subjected to the earthquake excitation with 0.1 g and 0.2 g amplitudes,no seismic damage is observed in the model slope,while the peak values of marginal spectra increase linearly with increasing slope height.In the case of 0.3 g seismic excitation,dynamic damage occurs near the slope crest and some rock blocks fall off the slope crest.When the seismic excitation reaches 0.4 g,the dynamic damage inside the model slope extends to the part with relative height of 0.295-0.6,and minor horizontal cracks occur in the middle part of the model slope.When the seismic excitation reaches 0.6 g,the damage further extends to the slope toe,and the damage inside the model slope extends to the part with relative height below 0.295,and the upper part(near the relative height of 0.8) slides outwards.Longitudinal fissures appear in the slope face,which connect with horizontal cracks,the weak intercalated layers at middle slope height are extruded out and the slope crest breaks up.The marginal spectrum identification results demonstrate that the dynamic damage near the slope face is minor as compared with that inside the model slope.The dynamic failure mode of counter-bedding rock slope with weak intercalated layers is extrusion and sliding at the middle rock strata.The research results of this paper are meaningful for the further understanding of the dynamic failure mode of counter-bedding rock slope with weak intercalated layers.

Calculation of Surface Excitation Parameters by a Monte Carlo Method

Electron inelastic mean free path （IMFP） is an important parameter for surface chemical quantification by surface electron spectroscopy techniques. It can be obtained from analysis of elastic peak electron spectroscopy （EPES） spectra measured on samples and a Monte Carlo simulation method. To obtain IMFP parameters with high accuracy, the surface excitation effect on the measured EPES spectra has to be quantified as a surface excitation parameter （SEP）, which can be calculated via a dielectric response theory. However, such calculated SEP does not include influence of elastic scattering of electrons inside samples during their incidence and emission processes, which should not be neglected simply in determining IMFP by an EPES method. In this work a Monte Carlo simulation method is employed to determine surface excitation parameter by taking account of the elastic scattering effect. The simulated SEPs for different primary energies are found to be in good agreement with the experiments particularly for larger incident or emission angles above 60° where the elastic scattering effect plays a more important role than those in smaller incident or emission angles. Based on these new SEPs, the IMFP measurement by EPES technique can provide more accurate data.

Evolution Property of Multisoliton Excitations for a Higher-Dimensional CoupledBurgers System

By means of the standard truncated Painlevé expansion and a special B?cklund transformation, the higher-dimensional coupled Burgers system (HDCB) is reduced to a linear equation, and an exact multisoliton excitation is derived. The evolution properties of the multisoliton excitation are investigated and some novel features or interesting behaviors are revealed. The results show that after interactions for dromion-dromion, solitoff-solitoff, and solitoff-dromion, they are combined with some new types of localized structures, which are similar to classic particles with completely nonelastic behaviors.