来自磁光阱中冷原子团的荧光干涉条纹及其应用

实验观察来自磁光阱中冷原子团的荧光经真空系统窗口的平板玻璃反射产生的干涉条纹，理论分析表明从从荧光干涉条纹的强度分布可获得关于俘获原子总数以及密度分布的信息。采用该方法实测了俘获原子总数，并模拟得到了不同密度分布时条纹的对比度变化。     

A Movable-Cavity Cold Atom Space Clock

We present an experimental scheme of a cold atom space clock with a movable cavity. By using a single microwave cavity, we find that the clock has a significant advantage, i.e. the longitudinal cavity phase shift is eliminated. A theoretical analysis has been carried out in terms of the relation between the atomic transition probability and the velocity of the moving cavity by taking into account the velocity distribution of cold atoms. The requirements for the microwave power and its stability for atomic π/2 excitation at different moving velocities of the cavity lead to the determination of the proper working parameters of the rubidium clock in frequency accuracy 10^-17. Finally, the mechanical stability for the scheme is analysed and the ways of solving the possible mechanical instability of the device are proposed.     

蒙特卡罗模拟四极阱中原子的参变激发

在中性原子的磁囚禁实验中,磁阱线圈的电流噪声会激发磁阱中的原子运动,势必对原子团的温度和寿命产生不可忽视的影响。对于非简谐阱,这种激发具有能量选择特性,它又取决于电流噪声的频谱分布。选择了实验中常用的四极阱为研究对象,用直接模拟蒙特卡罗方法来模拟四极阱中原子运动的参变激发现象,得到了原子温度与原子数损失随激发频率的变化关系,并进一步计算了两个共振峰处原子温度随调制时间和调制深度的变化曲线。此外,还研究了弹性碰撞速率对参变激发过程中原子温度上升的影响。这些结果对四极阱参变激发的实验有较好的参考价值。     

Parametric resonance and cooling on an atom chip

This paper observes the parametric excitation on atom chip by measuring the trap loss when applying a parametric modulation. By modulating the current in chip wires, it modulates not only the trap frequency but also the trap position. It shows that the strongest resonance occurs when the modulation frequency equals to the trap frequency. The resonance amplitude increases exponentially with modulation depth. Because the Z-trap is an anharmonic trap, there exists energy selective excitation which would cause parametric cooling. We confirm this effect by observing the temperature of atom cloud dropping.     

Bichromatic Coherent Population Trapping Under Hanle Configuration

We report the observation of bichromatic coherent population trapping under the transition ^87 RbFg = 1 → Fc = 0 with two linearly polarized laser beams by means of a Hanle effect configuration. The mechanism behind this effect is identified, and numerical solutions for the pump rates equations are presented.     

TEM01模式激光对两能级原子的作用力研究

推导了两能级原子在稳态和小速度一阶微扰近似下的受力矢量方程，并分析表明ＴＥＭ０１模光场以原子的作用力中存在旋涡力，对在大正失谐δ〉〉Ω０〉〉Г和ｚ〈〈ｚ０＝ｋｗ＾２／λ条件下的ＴＥＭ０１模行波和驻波场中原子的受力进行了分析，对行波场，自发辐射对原子运动的影响很大，但在ｒ〈〈λ区域内原子受到横向囚禁力；对驻波场，自发辐射的影响可以忽略，考虑在ｚ方向波长范围内原子的平均受力得到的结论为：在横向，除了有     

Coherent Scattering of Light by Bose-Einstein Condensation in a Tight Confinement

We have observed strong scattering of a probe light by dilute Bose-Einstein condensate （BEC） ^87Rb gas in a tight magnetic trap. The scattering light forms fringes at the image plane. It is found that we can infer the real size of the condensation and the number of the atoms by modelling the imaging system. We present a quantitative calculation of light scattering by the condensed atoms. The calculation shows that the experimental results agree well with the prediction of the generalized diffraction theory, and thus we can directly observe the phase transition of BEC in a tight trap.     

激光稳频技术的新发展(Ⅲ)──脉冲激光器的稳频技术和激光波长测量

脉冲激光器的频率稳定和测量,一向是一个较棘手的问题.但近年来,随着脉冲激光器在激光化学、激光光谱、激光雷达和外差检测系统等方面应用的发展,迫使人们去探索稳定脉冲光频的方法.下面介绍的几种脉冲激光稳频方法. 一、长期稳腔式[1]; 稳腔长当然可以稳定光频,但脉冲的持续时间短,较难判断腔长是否已被稳定,故采用一种长期稳腔的方案.这个方案在TEA CO2激光器中得到较合理实施,系统如图1所示,将TEA激光头和连续CO2器件置于同一谐振腔内,以构成混合式TEA激光器,获得单纵模振荡.通过连续器件的光电流稳频系统,以某一谱线(P或R的某一支…     

利用原子束研究光的力学效应

本文介绍了我们利用原子束研究光的力学效应的原理、方法和主要结果．我们测量了激光偏转原 子束的原子空间分布，观察了在光场作用下原子动量的扩散，验证了二能级原子共振荧光中亚泊松光子，统计分布，研究了慢原子在驻波场中的运动行为，提出了沟道原子光谱技术的新方法，并用这种方法观 察了钠原子的超精细结构．