BCH-代数的原子与分支

在BCH—代数中引入了原子与分支的概念，给出了一个元素为BCH-代数原子的一系列等价条件，证明了一个BCH—代数的所有原子作成的集合是一个广义结合BCI—代数，最后对BCH—代数分支的性质进行了讨论。     

基于扫描隧道显微镜的原子电子云结构

本文简要介绍了扫描隧道显微镜的基本工作原理，展示了一些扫描样品（石墨和铜）的电子云图，在简要介绍量子力学关于原子电子云结构基本理论的基础上，通过理论上的电子云结构与扫描结果的比较，在一定程度上验证了量子力学关于原子电子云结构理论的正确性．     

量子尺寸效应对原子表面扩散运动具有调制作用

近日，中科院物理所表面物理国家重点实验室SF4研究组及其合作者在薄膜生长动力学研究中取得新进展．他们从实验和理论上研究了Si（111）单晶衬底上Pb薄膜中的厚度变化对原子表面扩散运动的影响，证明了量子尺寸效应对原子表面扩散运动的调制作用．该成果被选作封面图片发表在美国《物理评论快报》上．     

Simultaneous Magneto-Optical Trapping of Fermionic ^40K and Bosonic ^87Rb Atoms

We report on simultaneous magneto-optical trapping of fermionic ^40K and bosonic 87Rb atoms. This trap is the first step towards quantum degenerate fermi gas ^40K. Laser lights for the two-species magneto-optical trap （MOT） are generated from diode lasers and tapered amplifier. The enriched ^40K dispenser is utilized in the experimental setup. We obtain up to 10^7 -10^8 ^40K and 10^8 -10^9 ^87Rb atoms respectively in the steady-state single-species MOT.     

Stimulated emission and multi-peaked absorption in a four level N-type atom

Absorption and refraction of the inner transition F₂\leftrightarrow F₃ of the closed four level N-type atom have been investigated under a weak field. The outer transitions F₁\leftrightarrow F₃ and F₂\leftrightarrow F₄ are resonantly interacted with drive field with frequency \omega_c and Rabi frequency \Omega_c, and saturation field with \Omega_s and \Omega_s, respectively. For the suitable Rabi frequencies \Omega_c and \Omega_s, we obtain the Mollow absorption spectrum of probe field. The reason is that the drive field excites the atom to the upper level F_c and simultaneously the saturation field takes the atom out of the lower level F₂, leading to the stimulated emission. Meanwhile, due to the dynamic energy splitting induced by the drive and saturation fields, the two- and four-peaked absorption spectra are observed. At the zero off-resonance detuning of probe field, we also find the transfer of dispersion from negative to positive with an increment of \Omega_s. Finally, the refractive index enhancement is predicted for a wide spectral region.     

Laser-diode excited intense upconversion luminescence of Er^3＋ in bismuth-lead-germanate glasses

We have investigated infrared-to-visible upconversion luminescence of Er^3＋ in bismuth-lead-germanate glasses. The UV cutoff wavelength is shortened while its lifetime is increased almost linearly, with PbF2 substituting for PbO in the bismuth-lead germanate glasses. Three emissions centred at around 529, 545 and 657 nm are clearly observed, which are identified as originating from the ^2H11/2→^4 I15/2,^4S3/2→^4 I15/2 and ^4 F9/2 →^4 I15/2 transitions, respectively. It is noted that all the upconversion emission intensities increase with PbF2 concentration increasing. The ratio between the intensities of red and green emissions increases with the increasing of PbF2 content. Energy transfer processes and nonradiative phonon-assisted decays account for the populations of the ^2 H11/2,^4 S3/2 and ^4F 9/2 levels. The quadratic dependence of fluorescence on excitation laser power confirms a two-photon process to contribute to the upconversion emissions.     

原子的波动性

激光冷却所达到的低温明确地显示出量子力学最使人着迷的结论之一:原子和其他一些实物粒子的波动性,这是路易·德布罗意早在1924年就预言了的①.越冷的粒子,越能显示出它们的波动性.近年来,两个新的很活跃的领域显示出与光的波动光学同样的效应:原子光学和原子干涉度量学.     

Population coherent control of Rydberg potassium atom via adiabatic passage

The time-dependent multilevel approach(TDMA) and B-spline expansion technique are used to study the coherent population transfer between the quantum states of a potassium atom by a single frequency-chirped microwave pulse.The Rydberg potassium atom energy levels of n=6-15,l=0-5 states in zero field are calculated and the results are in good agreement with other theoretical values.The time evolutions of the population transfer of the six states from n=70 to n=75 in different microwave fields are obtained.The results show that the coherent control of the population transfer from the lower states to the higher ones can be accomplished by optimizing the microwave pulse parameters.     

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.     

Total cross sections for electron scattering from sulfur compounds

The original additivity rule method cannot give good results for electron scattering from SO,SO2,SO2Cl2,SO2ClF,and SO2F2 molecules at low energy,because the electron-molecule scattering is simply reduced to electron-atom scattering.Considering the difference between the bound atom in a molecule and the corresponding free atom,the original additivity rule is revised.With the revised additivity rule,the total cross sections for electron scattering from these molecules are calculated over a wide energy range below 3000 eV and compared with the available experimental and theoretical data.A better agreement between them is obtained.