Magic Wavelength for Caesium Transition Line 6S1/2 - 6P3/2

We investigate the magic wavelengths of the trapping laser for 6S1/2 - 6P3/2 Of the Cs atom in a region where the optical shift between two different states can be elirninated. For fine levels and linear polarized laser they are 930.4 nrn and 937.2nm. The magic wavelengths range from 927. 7nrn to 945.0nm for circle-polarized perturbing laser. Effects of nuclear spin, the hyper-fine Zeernan levels, and the polarization of the light, which generate different magic wavelengths, are further discussed.     

Transferring the stability of iodine-stabilized diode laser at 634 nm to radio frequency by an optical frequency comb

An optical flequency comb phase-locked on an iodine frequency stabilized diode laser at 634 nm is constructed to transfer the accuracy and stability from the optical domain to the radio frequency domain. An external-cavity diode laser is frequency-stabilized on the Doppler-free absorption signals of the hyperfine transition R（80）8-4 using the third-harmonic detection technique. The instability of the ultra-stable optical oscillator is determined to be 7 ×10^-12 by a cesium atomic clock via the optical frequency comb＇s mass frequencv dividing technique.     

Ultra-Stable Rubidium-Stabilized External-Cavity Diode Laser Based on the Modulation Transfer Spectroscopy Technique

We construct an ultra-stable external-cavity diode laser via modulation transfer spectroscopy referencing on a hyperfine component of the ST Rb D2 lines at 780 nm. The Doppler-free dispersion-like modulation transfer signal is obtained with high signal-to-noise-ratio. The instability of the laser frequency is measured by beating with an optical frequency comb which is phase-locked to an ultra-stable oven controlled crystal oscillator. The Allan deviation is 3.9 × 10-13 at I s averaging time and 9.8 ×10-14 at 90s averaging time.     

High Field Seeking State Atom Laser and Properties of Flux

We present an experimental study on the continuous atom laser. The experiments show that a high field seeking state atom laser with stable flux can be formed by increasing the strength of outcoupling before large density fluctuations appear. It is easy to obtain a long length or high speed output with this kind of atom laser.     

Momentum filtering scheme of cooling atomic clouds for the Chinese Space Station

To obtain cold atom samples with temperatures lower than 100 pK in the cold atom physics rack experiment of the Chinese Space Station, we propose to use the momentum filtering method for deep cooling of atoms. This paper introduces the experimental results of the momentum filtering method verified by our ground testing system. In the experiment, we designed a specific experimental sequence of standing-wave light pulses to control the temperature, atomic number,and size of the atomic cloud. The r...     

原子激光器研究的最新结果

１９９５年,在捕获原子的稀薄气体中玻色－爱因斯坦凝聚（ＢＥＣ）的实现,表明宏观数量的玻色粒子处在了单一的量子能态,宏观气体可以用单个波函数来描述．和激光腔中单一模式对光子的储存相类似,ＢＥＣ可看作被宏观布居的样品原子所占有的量子态．在激光中,用部分反射镜将相干光子束耦合出激光腔形成了激光,对应地,美国ＭＩＴ小组在１９９７年用射频耦合方式将原子从ＢＥＣ中输出,实现了原子激光器．这种激光器输出的是空间分布呈月牙形的原子脉冲,并且,在两团ＢＥＣ原子下落的相互重叠区用吸收成像法清楚地观测到了高反衬度的干…     

High-performance laser power feedback control system for cold atom physics

A laser power feedback control system that features fast response,large-scale performance,low noise,and excellent stability is presented. Some essential points used for optimization are described. Primary optical lattice experiments are given as examples to show the performance of this system. With these performance characteristics,the power control system is useful for applications in cold atom physics and precision measurements.     

用吸收成像法分析玻色-爱因斯坦凝聚的逃逸蒸发冷却

本文介绍利用吸收成像法得到的光学厚度来作为是否进行有效蒸发冷却的判据的基本原理.利用蒸发冷却实现BEC的过程中,过快或过慢的降低磁阱深度,都会带来大量的原子数损失和低的蒸发冷却效率.蒸发冷却过程必须是一个满足逃逸蒸发冷却(runaway evaporation)条件的有效的过程.利用光学厚度和弹性碰撞率之间的关系,可直接用吸收成像法分析蒸发冷却过程是否有效.文中还结合北京大学量子信息与测量实验室实现BEC的实验数据加以说明.     

噪声间关联对原子激光谱密度的影响

在描述原子激光强度的速率方程中，考虑了量子噪声和热噪声、以及它们的关联以后，计算了原子激光的关联函数和功率谱密度。发现不仅噪声对原子激光的统计性质有影响，而且，噪声间的关联会使得原子激光的谱密度发生从单峰到双峰、或三峰的相变。这种相变可以用凝聚体干涉条纹间距的变化来观察。进一步又讨论了噪声的关联时间对原子激光谱密度的影响。