第I种非对称三态叠加多模叠加态光场的高次和压缩——第一正交分量的N次方H压缩效应

构造了第孙中禹种强度不等的非对称三态叠加多模叠加态光场|ψ₁^(ABC)〉_q.利用多模压缩态理论研究了态|ψ₁^(ABC)〉_q第一正交分量高次和压缩.结果发现:①当构成态|ψ₁^(ABC)〉_q的三个多模相干态光场的强度不相等时,在一定条件下,态|ψ₁^(ABC)〉_q的第一正交分量可出现任意幂次的高次和压缩.②当上述的三个多模相干态光场强度相等时,态|ψ₁^(ABC)〉_q的第一正交分量的高次和压缩现象消失.在这种情况下,态|ψ₁^(ABC)〉_q的第一正交分量恒处于NH最小测不准态.     

两不同奇相干态组成的第种四态叠加多模叠加态光场的等阶N次方Y压缩

根据量子力学中的线性叠加原理,构造了由多模奇相干态与多模复共轭奇相干态这两种不同的奇相干态的线性叠加所组成的第Ⅰ种四态叠加多模叠加态光场|Ψ_o⁽⁴⁾,I〉_q,利用多模压缩态理论,研究了态|Ψ_o⁽⁴⁾,I〉_q的等阶N次方Y压缩特性.结果发现:1)当压缩阶数N为偶数时,在不同的条件下,态|Ψ_o⁽⁴⁾,I〉_q可分别呈现三种状态:a)态|Ψ_o⁽⁴⁾,I〉_q可处于等阶N-Y最小测不准态;b)态|Ψ(4)o,I〉q的第一正交分量可呈现等阶N次方Y压缩效应;c)态|Ψ_o⁽⁴⁾,I〉_q可呈现“半相干态”效应.2)当压缩阶数为奇数时,若果r₁=r₂=r,则在不同的条件下,态|Ψ_o⁽⁴⁾,I〉_q可分别呈现三种状态:a)态|Ψ_o⁽⁴⁾,I〉_q可处于等阶N-Y最小测不准态;b)态|Ψ_o⁽⁴⁾,I〉_q的第一正交分量可呈现等阶N次方Y压缩效应;c)态|Ψ_o⁽⁴⁾,I〉_q的第二正交分量可呈现等阶N次方Y压缩效应.3)“半相干态”是指在一定条件下,态|Ψ_o⁽⁴⁾,I〉_q的两个正交分量其中一个正交分量处于等阶N-Y最小测不准态,另一个正交分量既不处于等阶N-Y最小测不准态也不呈现等阶N次方Y压缩效应.     

自聚焦透镜准直应用的长度计算与实验

根据近轴子午光线方程,研究了自聚焦透镜准直应用。在未知n_o和A~(1/2)值情况下,本文提出解决准直应用自聚焦透镜长度计算问题。     

k光子Jaynes-Cummings模型的亚Poisson光子统计特性研究

本文利用量子电动力学理论,首次对 k 光子 Jaynes-Cummings 模型中单模激光场的稳态亚 Poisson 光子统计性质进行了系统研究.结果表明:在一般情况下,激光上能级相对泵浦参量 x_a 具有一个确定的阈值 x_at;当 x_a>x_at时,光场呈现亚 Poisson 光子统计;当 x_a>>x_at时,光场呈现出深度且完全恒定的亚 Poisson 光子统计.在特殊情况下,阈值 x_at-0,这时在激光腔内将直接诱发亚 Poisson 光子统计.随着 k(k≥2)值增加,阈值 x_at降低,光场亚 Poisson 光子统计程度增强.     

多通道声光偏转选址开关

本文报道1×N多通道声光偏转选址开关的研究.由 Ti 扩散 LiNbO₃波导上两个短程透镜和一个倾斜 chirp 叉指换能器构成的集成光学声光偏转器,在两端分别对接一根和N根单模光纤时,用作多通道选址开关,在换能器带宽为200MHz,对1.3μm波长,可实现N=24;带宽增加到500MHz,可达到N=64,在波长为0.633μm的 He-Ne 激光下进行的实验和理论符合.     

态|ψ3(3)〉q中广义磁场分量的N次方Y压缩效应

构造了由多模复共轭相干态|{Z_j^*}〉_q、多模复共轭虚相干态|{iZ_j^*}〉_q和多模真空态|{Q_j} 〉_q这三态的线性叠加所组成的第Ⅲ类三态叠加多模叠加态光场|ψ₃⁽³⁾〉_q.利用多模压缩态理论研究了态|ψ₃⁽³⁾〉_q中广义磁场分量的任意偶数次广义非线性等幂次N次方Y压缩特性.结果发现:在压缩次数N取偶数,只要各模的初始相位φ_j(j=1,2,3,…,…,q),态间的初始相位差(θ_i-θ₂)(i=1,3)和各单模相干态光场平均光子数R_j²之和 分别满足各自的取值条件,态|ψ₃⁽³⁾〉_q的广义磁场分量(即第一正交相位分量)就可呈现出周期性变化的、任意偶数次的广义非线性等幂次N次方Y压缩效应.     

四态叠加多模叠加态光场|Ψe(4),Ⅲ〉q的等阶N次方Y压缩

根据量子力学的线性叠加原理,构造了由多模偶相干态与多模虚偶相干态组成的第Ⅲ种四态叠加多模叠加态光场态|Ψ_e⁽⁴⁾,Ⅲ〉_q的等阶N次方Y压缩特性.结果发现:1) 当压缩阶数N=4m,(m=1,2,3,…)时,态|Ψ_e⁽⁴⁾,Ⅲ〉_q恒处于等阶数N-Y最小测不准态;2) 当压缩阶数N=4m′+2,(m′=0,1,2,…)时,在(θ₁-θ₂),q,R_j,r₁,r₂等取不同的组合定值下,态|Ψ_e⁽⁴⁾,Ⅲ〉_q可分别呈现出等阶N次方Y压缩效应与"半相干态"效应;3) 当压缩阶数N为奇数时,在(θ₁-θ₂),q,R_j,r₁,r₂等取不同的组合定值下,态|Ψ_e⁽⁴⁾,Ⅲ〉_q可呈现出等阶N次方Y压缩效应.     

多模双参数变形相干态

借助一个满足量子Heisenberg-Weyl代数(H-W_q,s代数)的多模算符,给出了量子代数SU(2)_q,s和SU(1,1)_q,s的k(k≥2)模实现,并构造了相应的相干态.     

两参数变形量子代数SU(1,1)q,s的相干态及其性质

利用SU(1,1)_q,s量子代数的两参数变形振子构造出归一化的SU(1,1)_q,s相干态,证明了SU(1,1)_q,s量子代数的表示基是正交的,并讨论了它的相干态的归一性和完备性。指出(SU(1,1)_q,s相干态的相干性受参数q、s的影响。     

PECVDSi3N4/InP界面特性的研究

本文利用Auger分析技术和C-V测量方法,详细地研究了PECVDSi₃N₄/InP界面特性,Auger能谱分析表明热处理使界面面发生互扩散,同时InP的热分解导致P元素穿过Si₃N₄薄膜到达表面。C-V测量表明Ag/Si₃N₄/InPMIS结构可以实现载流子的堆积、耗尽和反型。     

Structured mirror array for two-dimensional collimation of a chromium beam in atom lithography

Direct-write atom lithography,one of the potential nanofabrication techniques,is restricted by some difficulties in producing optical masks for the deposition of complex structures.In order to make further progress,a structured mirror array is developed to transversely collimate the chromium atomic beam in two dimensions.The best collimation is obtained when the laser red detunes by natural line-width of transition 7S3 → 7P40 of the chromium atom.The collimation ratio is 0.45 vertically(in x axis),and it is 0.55 horizontally(in y axis).The theoretical model is also simulated,and success of our structured mirror array is achieved.     

Lifetime of metastable fluorine atoms

For laser collimation of neutral F atoms, a resonance transition cycle between the metastable and the upper excited states (3s⁴ P _5/2?3p⁴ D ⁰ _7/2) can be used as a two-level closed system. We have determined the lifetime of the metastable state (3s⁴ P _5/2) in F atoms by measuring the decay curve of the fluorescence intensity as a function of distance from the plasma source. Combining the measured velocity of F radicals from the Doppler shift of the fluorescence peak, we have obtained the lifetime of the F metastable state as 3.7±0.5 μs. With this short metastable lifetime of F radicals, the simple Doppler cooling method using spontaneous light force is not practical for laser collimation of F radicals. Use of stimulated light force may be necessary to collimate F radical beams in a short distance. Received: 4 July 2000 / Published online: 13 September 2000     

Study of Scintillation for Infrared Laser Beam Propagating in Atmospheric Turbulence on Earth-Space Paths

On earth-space paths, by applying a modification of the Rytov method that incorporates spatial frequency filter function under strong atmosphere fluctuation conditions, a tractable model is developed for the scintillation index of infrared laser Gaussian beam wave that is valid under moderate-to-strong irradiance fluctuations. At Infrared band, based on ITU-R C ² _n model, the scintillation indexes for collimation laser beam are predicted by this analytic model. The results agree with theoretic expected scintillation. This scintillation model can be converted into a plane or a sphere wave scintillation index model on earth-space paths, and also reduced to a Gaussian beam wave model on horizontal sight paths of invariable C ² _n.     

Effect of collimator size and absorber thickness on gamma ray attenuation measurements for bakelite and perspex

The mass attenuation coefficient (μ _m) of 662 keV gamma rays have been measured in the extended media of bakelite and perspex under different collimation conditions. The increase in attenuation coefficient is seen with increase in sample thickness as well as with collimator size due to the contribution of multiple scattered photons in the uncollided beam of 662 keV gamma rays.     

超短激光脉冲驱动的Thomson散射空间分布特性

研究了超短激光脉冲驱动的Thomson散射的辐射空间分布. 发现辐射的空间分布对称性显著地依赖于超短脉冲的载波相位η₀，在η₀＝0，π时，辐射的空间分布呈现出二重或一重对称性；而在其他载波相位时，这些空间分布对称性遭到破坏. 辐射光的准直性也依赖于驱动脉冲的载波相位，在η₀＝±π/2时辐射光的准直性最好. 这些结果表明可以通过改变驱动激光脉冲的载波相位来控制辐射光的空间分布，也可以利用辐射空间分布对相位的依赖特性来测量超短激光脉冲的载波相位. 关键词： Thomson散射 空间分布 载波相位     

Sub-megabar Mössbauer studies using diamond anvil cells

The development and the use of the diamond anvil cell for Mössbauer Spectroscopy (MS) to pressures nearing 100 GPa are discussed. Three types of cells and their typical performance are given. Pressure calibration, hydrostatic media, gasketing, collimation, -ray absorption, and sample size for MS are reviewed. New MS results showing hysteresis in the room temperature high pressure transition in iron and showing the rapid rise ofT _N in NiI₂ with pressure are presented.     

2D laser collimation of a cold Cs beam induced by a transverse <Emphasis Type="Italic">B</Emphasis> field

We describe transverse collimation of a continuous cold cesium beam (longitudinal temperature 75 μK) induced by a two-dimensional, blue-detuned near-resonant optical lattice. The mechanism described for a lin-‖-lin configuration is made possible by the application of a transverse magnetic field B_⊥. The phenomenon described differs from gray molasses, for which any small magnetic field degrades cooling, as well as from magnetically induced laser cooling in red-detuned optical molasses, where there are no dark states. The lowest transverse temperature is experimentally found to vary as B _⊥ ² . The collimated flux density shows a dip as a function of B_⊥, the width of which is proportional to the cube root of the laser intensity, general features predicted by our semiclassical model. This technique provides a sensitive tool for canceling transverse magnetic fields in situ at the milligauss level.     

自聚焦透镜组合光学系统的光线传输分析

本文导出了自聚焦透镜组合光学系统的光线传输方程,讨论了光线传输与自聚焦透焦透镜参数关系。对几种典型自聚焦透镜组合进行了计算、从而估计自聚焦透镜参数选择。     

A Comparative study of p-Em and C12-Em interactions at 4·5 GeV/c per nucleon

In this paper we present a comparative study of inelastic interactions of C¹²-Em and p-Em at 4·5 GeV/c per nucleon. The multiplicity distributions and their correlations have been studied. The results show a strong correlation of n _s onn _h in the case of C¹²-Em but not in the case of p-Em. It is also shown that the n _s increases with the increase of the projectile mass. The angular distribution of the target fragments in C¹²-Em shows a massive forward collimation. Comparison is also made in the pseudorapidity distribution of both C¹²-Em and p-Em, the result shows many interesting features.