Lu Yukai, Holland Connor M, Cheuk Lawrence W
Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Phys Rev Lett. 2022 May 27;128(21):213201. doi: 10.1103/PhysRevLett.128.213201.
Recent work with laser-cooled molecules in attractive optical traps has shown that the differential ac Stark shifts arising from the trap light itself can become problematic, limiting collisional shielding efficiencies, rotational coherence times, and laser-cooling temperatures. In this Letter, we explore trapping and laser cooling of CaF molecules in a ring-shaped repulsive optical trap. The observed dependences of loss rates on temperature and barrier height show characteristic behavior of repulsive traps and indicate strongly suppressed average ac Stark shifts. Within the trap, we find that Λ-enhanced gray molasses cooling is effective, producing similar minimum temperatures as those obtained in free space. By combining in-trap laser cooling with dynamical reshaping of the trap, we also present a method that allows highly efficient and rapid transfer from molecular magneto-optical traps into conventional attractive optical traps, which has been an outstanding challenge for experiments to date. Notably, our method could allow nearly lossless transfer over millisecond timescales.
最近在吸引性光学阱中对激光冷却分子的研究表明，阱光本身产生的差分交流斯塔克位移可能会成为问题，限制碰撞屏蔽效率、旋转相干时间和激光冷却温度。在本信函中，我们探索了在环形排斥性光学阱中捕获和激光冷却CaF分子。观察到的损失率对温度和势垒高度的依赖性显示出排斥性阱的特征行为，并表明平均交流斯塔克位移得到了强烈抑制。在阱内，我们发现Λ增强灰糖浆冷却有效，产生的最低温度与在自由空间中获得的相似。通过将阱内激光冷却与阱的动态重塑相结合，我们还提出了一种方法，该方法允许从分子磁光阱高效快速地转移到传统的吸引性光学阱中，这是迄今为止实验中一项突出的挑战。值得注意的是，我们的方法可以在毫秒时间尺度上实现几乎无损的转移。
