Physics of Laser Cooling and Atomic Gas BEC

A3项目的主要成果是与铷原子BEC相关的物理。A3分为三组操作。Kuga等人致力于(1)在日本首次实现BEC，(2)与BEC相关的物理学，(3)改进BEC设备的开发，以及(4)结合激光冷却原子和微腔的腔量子电动力学。(1)首先在高真空条件下收集预冷Rb原子，将原子转移到磁阱中，绝热压缩原子云，然后进行蒸发冷却。(2)进行了三个实验。BEC原子在驻波中的衍射表现为Raman-Nath、Bragg和Stern-Gerlach型衍射。马赫-珍德式原子干涉仪的演示。（三）利用原子-光子四波混频放大相干原子波。(3)为了增加BEC的亮度，他们开发了一种塞曼慢速器，可以以20m/s的速度连续每秒提供10^11个原子。(4)将约10个激光冷却的Rb原子引入间距为70微米的微腔中。他们观察到激光脉冲在腔内的阈下和阈上的传播。平野等人研究了Rb BEC的物理性质。(1)均匀非谐振激光束照射时BEC的动力学。(2)单束光偶极子阱中BEC云的振荡。Sasada等人开发了一种新型的冷亚稳态氦原子束源，该源通过低温冷却氦气的放电获得。他们还研究了拉盖尔-高斯激光束，该激光束将用于暗光阱和波导。

The main achievement of the A3 project was the physics related to the rubidium atoms BEC. The A3 was operated by three groups. Kuga et al worked on (1) the first realization of BEC in Japan, (2) physics related to the BEC, (3) the development of an improved BEC apparatus, and (4) the cavity quantum electrodynamics that combines a laser cooled atom and a microcavity. (1) The BEC was achieved, first, by collecting pre-cooled Rb atoms under a high vacuum, transferring atoms into a magnetic trap, adiabatically compress the atomic cloud, and then, by evaporative cooling. (2) Three experiments were done. (I) the diffraction of BEC atoms in a standing wave of light that demonstrated Raman-Nath, Bragg, and Stern-Gerlach type diffractions. (ii) Demonstration of a Mach Zhender type atom interferometer. (iii) The amplification of a coherent atomic wave by using atom-photon four wave mixing. (3) To increase the luminosity of the BEC, they developed a Zeeman slower that can supply 10^11 atoms per seconds continuously at the speed of 20m/s. (4) Approximately 10 laser cooled Rb atoms were introduced into a micro-cavity of 70microm meter spacing. They observed both subliminal and superliminal propagations of a laser pulse through the cavity. Hirano et al worked on the physics of the Rb BEC. (1) Dynamics of BEC when an uniform off-resonant laser beam is illuminated. (2) The oscillation of BEC cloud in a single beam optical dipole trap. Sasada et al developed a new type of cold metastable He atomic beam source that was obtained through the discharge of cryogenically cooled helium gas. They worked also on the Laguerre-Gauss laser beam that is to be used for a dark optical trap and guide.