Investigation of coherent manipulations in ultracold thermal and Bose-Einstein condensed molecular gases

该研究项目将从理论上研究通过光结合产生分子玻色-爱因斯坦凝聚物。这可以建立在广泛的光关联知识的基础上，并研究凝聚态和冷热系综之间的异同。在分子形成中，原子间的相关性变得重要，玻色-爱因斯坦凝聚体的有效平均场描述变得无效。F. masnow - seeuws （CNRS Laboratoire aim<s:1> Cotton, Orsay）小组目前开发了一种场论方法，考虑到由于两个碰撞原子相互作用势的空间依赖性而产生的对相关性。这种方法应扩展到包括激光场的时间依赖性和非凝聚原子的存在。R. Kosloff（耶路撒冷希伯来大学）团队的最优控制理论方法可以用来优化稳定的分子玻色-爱因斯坦凝聚物的产生，并预测光缔合速率。根据激光脉冲参数，可以分离分子形成和凝聚动力学的时间尺度。然后可以将未凝聚的原子当作热浴处理。概述的方法应适用于Na2（钠二聚体）和Cs2（铯二聚体）的光缔合。将该方法推广到偶极分子，如异核碱二聚体，应进行研究。

The research project will theoretically investigate the creation of a molecular Bose-Einstein condensate by means of photoassociation. This allows to build on the extensive knowledge of photoassociation and to investigate similarities and differences between a condensate and a cold thermal ensemble. In molecule formation, correlations between atoms become important, and effective mean-field descriptions of Bose-Einstein condensates become invalid. A field theoretical approach currently developed in the group of F. Masnou-Seeuws (CNRS Laboratoire Aimé Cotton, Orsay), takes into account pair correlations due to the spatial dependence of the interaction potential of two colliding atoms. This approach shall be extended to include a time-dependence of the laser field and the presence of non-condensed atoms. The optimal control theory approach of the group of R. Kosloff (Hebrew University Jerusalem) can then be employed to optimize the creation of a stable molecular Bose-Einstein condensate and to predict photoassociation rates. Depending on the laser pulse parameters, the timescales of molecule formation and condensate dynamics can be separated. The noncondensed atoms can then be treated as a thermal bath. The outlined methodology shall be applied to photoassociation of Na2 (sodium dimer) and Cs2 (cesium dimer). The extension of the method to dipolar molecules such as heteronuclear alkali dimers shall be investigated.