物理学报2016，Vol.65Issue(11)：114101-1-114101-10,10.DOI:10.7498/aps.65.114101
亚微米局域空心光束的产生及其在单原子囚禁与冷却中的应用理论研究∗
Theoretical research on the generation of a submicron lo calized hollow b eam and its applications in the trapping and co oling of a single atom
摘要
Abstract
In order to generate a submicron localized hollow laser beam and realize the more efficient laser cooling and trapping of a single atom, a simple and promising scheme with using the system of a single mode fiber a circle binary phase plate and a microlens is proposed in this paper. From Rayleigh-Sommerfeld diffraction theory, the intensity distribution of the generated localized hollow laser beam near the focal plane and its propagating properties in free space are calculated. Also, the dependences of the dark-spot size of the localized hollow beam on the mode radius of single mode fiber and the focal length of the mocrolens are studied. The calculated results show that the intensity distribution of the localized hollow beam presents approximately symmstrical distribution near the focal plane. In the center of the focal plane, the light intensity is 0 and increases gradually around it. So a closed spherical light field (i.e., localized hollow laser beam) with a radius of 0.4 µm is generated. The calculated results also show that the dark-spot size of the localized hollow laser beam decreases with the increasing of the microlens focal length and the decreasing of the single mode fiber mode radius. So proper parameters of this optical system can be chosen to generate localized hollow laser beams with different sizes for various applications. When the localized hollow laser beam is blue detuned, atoms will be trapped in the minimum light filed. If a repumping laser beam is applied, the trapped atoms will be also cooled by the intensity-gradient Sisyphus cooling. In this paper, we build a device for trapping and cooling a single atom by using the generated blue detuned submicron localized hollow laser beam. We study the dynamical process of intensity-gradient cooling of a single 87Rb atom trapped in the localized hollow beam by Monte-Carlo method. Our study shows that a single 87Rb atom with a temperature of 120 µK (the corresponding momentum is 30~k) from a magneto-optical trap (MOT) can be directly cooled to a final tempreture of ∼5.8 µK (the corresponding momentum is ∼ 6.6~k). So an ultracold single atom is generated and trapped in our submicro localized hollow beam. This device for obtaining ultralcold single atom can be widely uesd in the regions of the optical physics, the atom and molecule optics, such as the detecting of the fundamental physical parameters, realizing the quantum computer, studying the cold collision of singe atoms, and realizing the single atom laser.关键词
亚微米/局域空心光束/单原子/强度梯度冷却Key words
submicron/localized hollow beam/single atom/intensity-gradient cooling引用本文复制引用
任瑞敏,尹亚玲,王志章,郭超修,印建平..亚微米局域空心光束的产生及其在单原子囚禁与冷却中的应用理论研究∗[J].物理学报,2016,65(11):114101-1-114101-10,10.基金项目
国家自然科学基金(批准号:11274114)资助的课题.@@@@* Project supported by the National Natural Science Foundation of China (Grant No.11274114) （批准号:11274114）
