分子体系激光冷却的机理和方法的高精度理论研究

Owing to the exciting potential applications of ultracold molecules and molecular ions in many fields, developing new cooling schemes has attracted great interests in recent years. However, the successful direct laser cooling has been achieved in only a few neutral and charged molecules. In fact, although laser cooling of atomic systems is nowadays a rather well-established experimental technique, many nonmetal atoms can not be cooled to the ultracold regime. We plan to choose a series of molecular systems as our research objects. Direct laser cooling of them will be investigated by using highly accurate ab initio and dynamical calculations including the spin–orbit coupling and non-adiabatic effects.The research results will have great importance in revealing the essential characteristics of the laser cooling processes, guiding experiments and acquiring novel insights in the laser cooling.mechanisms.

超冷分子与精密测量、量子计算和量子通讯等诸多应用领域密切相关，因此近年来分子体系的冷却引起了人们的广泛关注。然而由于内态结构的复杂性，分子体系的激光冷却十分困难，目前仅有极少数分子实现了激光冷却。我们拟使用包含旋轨耦合效应的高精度从头算和非绝热动力学方法研究一系列分子的激光冷却可行性，寻找新的适合激光冷却的体系，提出中性分子平动冷却和分子离子内态冷却的机制，并设计检测分子体系冷却效果的方案。研究结果对于揭示激光冷却过程的本质特征, 解释和指导实验，获得对激光冷却机理的新认识具有重要的意义。

超冷分子在精密测量、量子计算等诸多领域都有潜在应用价值，但目前仅有有限的几种分子在实验上通过激光冷却的方法实现了达到超冷的目标，这源于分子内态结构的复杂性所带来的困难。本项目使用包含旋轨耦合效应的高精度从头算和量子动力学方法研究了一系列分子的激光冷却可行性，找到并确立了CaCCH、SrCCH、SiH和PH等新的极佳的候选超冷分子体系，构建了可达超冷的激光冷却方案，为相关实验提供了重要参考。特别是，基于所获研究结果，提出了分子激光冷却的第四个准则，归纳出了“交叉点下移”的经验规律。本项目的研究取得了一系列成果，已在重要学术刊物发表了10篇论文，获得了有意义的发现。这些研究成果对于揭示激光冷却过程的特征，解释和指导实验，获得对激光冷却机理的新认识具有重要意义。