物理学报2016，Vol.65Issue(9)：093201-0-093201-7,8.DOI:10.7498/aps.65.093201
磁光阱中超冷钠-铯原子碰撞的实验研究∗
Ultracold collisions in a dual species 23Na-133Cs magneto-optical trap
摘要
Abstract
The production and research of ultracold heteronuclear molecules have aroused the great interest recently. On the one hand, these molecules are extremely popular in experiments for exploring the collision dynamic behaviors in threshold, photoassociative spectrum and strong dipole-dipole interactions. On the other hand, ultracold polar molecules populated at deeply bound levels in the singlet ground state are the right candidates to investigate quantum memories for quantum simulation, and to study strongly interacting quantum degenerate gases. The precise knowledge of cold collision processes between two different types of alkali atoms is necessary for understanding and utilizing ultracold heteronuclear molecules, sympathetic cooling, and thus formation of two species BEC. The goal of the present investigation is to study the collisions between ultracold sodium atoms and cesium atoms. We systematically demonstrate simultaneously trapping ultracold sodium and cesium atoms in a dual-species magneto-optical trap (MOT). The sodium atom trap loss rate coefficient βNa-Cs is measured as a function of Na trapping laser intensity. At low intensities, the trap loss is dominated by ground-state hyperfine-changing collisions, while at high intensities, collisions involving excited atoms are more important. A strong interspecies collision-induced loss for Na atoms in the MOT is observed. In order to obtain the trap loss coefficient βNa-Cs, we proceed in two steps. First, the Cs repumping laser is blocked to avoid the formation of ultraold Cs atoms. The loading process of Na atoms is recorded when the Cs trapping laser is on. Second, the loading curves of the Na atoms are obtained as Cs atoms are present with the repumping laser beams. The total losses PNa and P′Na are acquired by fitting the two loading curves of trapped Na atoms. Thus, the trap loss coefficientβNa-Cs can be derived from the difference between total losses PNa and P′Na divided by the density of the Cs atoms. The coefficient βNa-Cs decreases in a range of 5–10 mW/cm2, which originates from the hyperfine-state changing (HFC) collision. A Doppler model is used to calculate the Na atom trap depth, in that the atom trap depth and exoergic energy determine the behavior of the collisional trap loss rate coefficient. The three corresponding calculated critical intensities of Na trapping laser are 7.98, 14.82, 16.2 mW/cm2 respectively in the Na-Cs HFC collision process. The first calculated critical intensity value agrees well with the experimental result. Our work provides a valuable insight into HFC collision between Na and Cs atoms and also paves the way for the production of ultracold NaCs molecules using Photoassociation (PA) technology. Furthermore, the experimental results lay a great basis for the obtainments of high sensitive heteronuclear NaCs molecular PA spectrum and the creation of deeply bound ground state molecules.关键词
磁光阱/超冷钠原子/超冷铯原子/超冷碰撞Key words
magneto-optical trap/ultracold sodium atoms/ultracold cesium atoms/ultracold collisions引用本文复制引用
徐润东,刘文良,武寄洲,马杰,肖连团,贾锁堂..磁光阱中超冷钠-铯原子碰撞的实验研究∗[J].物理学报,2016,65(9):093201-0-093201-7,8.基金项目
国家重点基础研究发展计划(批准号:2012CB921603)、长江学者和创新团队发展计划(批准号：IRT13076)、基金委重大研究计划培育项目(批准号:91436108)、国家自然科学基金(批准号:61378014,61308023,61378015,11434007)、教育部新教师基金(批准号:20131401120012)、国家自然科学基金国家基础科学人才培养基金(批准号：J1103210)、山西省优秀青年学术带头人和山西省青年科技研究基金(批准号:2013021005-1)资助的课题 （批准号:2012CB921603）
