碱土金属、稀土金属和硼族元素卤化物中适合激光冷却双原子分子的理论研究

Experimental preparation and theoretical research of ultracold molecules have been one of the frontier in the field of atomic, molecular and optical (AMO) physics, precision measurement physics and quantum information science. Recently, there is growing attention on laser cooling of diatomic polar molecules with the first direct cooling of SrF by Doppler and Sisyphus cooling. Naturally, the theoretical studies of potential laser cooling candidates become more and more important. However, most investigators are inclined to identify potential laser cooling candidates only by two factors, a strongly diagonal Franck-Condon factors (FCFs) and shortly radiative lifetime. They usually ignore the rotational energy levels, the fine and hyperfine structures of diatomic polar molecules. And the studies of the Stark shift as well as Zeeman shift of diatomic polar molecules in an applied external field are not available in the literature to the best of our knowledge. In the work,we investigate the feasibility of laser cooling alkaline-earth metal halide, rare earth halid and halide of boron group elements using ab initio quantum chemistry. Furthermore, we propose laser cooling schemes for potential laser cooling candidates. According to the calculation results, the effect of the rotational energy levels, the fine and hyperfine structures, the Stark shift as well as Zeeman shift in an applied external field of diatomic polar molecules on laser cooling should be well understood. We expect some valuable instructions can be provided for the experimental preparation and theoretical research of ultracold molecules.

随着SrF分子激光冷却和磁光囚禁的实现，双原子分子激光冷却的实验制备与理论研究近年来已成为原子分子与光学物理、精密测量物理和量子信息科学等领域中的前沿研究热点之一。理论上鉴别适合激光冷却的双原子分子候选对象是最先需要解决的问题，但目前已有的理论研究较为零散，缺乏系统性，且主要只是通过高对角化的Franck-Condon因子和较短辐射寿命这两个条件鉴别出适合激光冷却的候选分子，而对于候选分子的精细结构和超精细结构、转动能级以及在静电场下的斯塔克移动和静磁场下的塞曼移动则鲜有报道。本项目将在我们之前的理论研究基础上采用从头算计算方法，重点研究碱土金属、稀土金属和硼族元素的卤化物系列，鉴别出适合激光冷却的双原子分子候选对象，并为候选对象提出激光冷却方案，深入探讨分子的精细结构和超精细结构、转动能级和在外场作用下的能级移动对激光冷却的影响效应，为双原子分子激光冷却的实验制备提供若干指导原则。

随着SrF分子激光冷却和磁光囚禁的实现，双原子分子激光冷却的实验制备与理论研究近年来已成为原子分子与光学物理、精密测量物理和量子信息科学等领域中的前沿研究热点之一。理论上鉴别适合激光冷却的双原子分子候选对象是最先需要解决的问题。本项目采用从头算计算方法，已完成对碱土金属和硼族元素的卤化物/氢化物体系的研究，鉴别出适合激光冷却的双原子分子候选对象，并为候选对象提出激光冷却方案，并已探讨分子的精细结构和超精细结构、转动能级和在外场作用下的能级移动对激光冷却的影响效应，为双原子分子激光冷却的实验制备提供若干指导原则。