Piest B, Vollenkemper V, Böhm J, Herbst A, Rasel E M
Institut für Quantenoptik, Gottfried Wilhelm Leibniz Universität, Welfengarten 1, 30167 Hannover, Germany.
Rev Sci Instrum. 2022 Feb 1;93(2):023202. doi: 10.1063/5.0071619.
We exploit red- and blue-detuned magneto-optical trapping (MOT) of Rb benefitting from a simplified setup and a novel approach based on liquid crystal variable retarders (LCVR). To maintain the trapping forces when switching from a red- to a blue-detuned MOT, the handedness of the circular polarization of the cooling beams needs to be reversed. LCVRs allow fast polarization control and represent compact, simple, and cost-efficient components, which can easily be implemented in existing laser systems. This way, we achieve a blue-detuned type-II MOT for 8.7 × 10 atoms of Rb with sub-Doppler temperatures of 44 μK well below the temperatures reached in a conventional Rb type-I MOT. The phase space density is increased by more than two orders of magnitude compared to the standard red-detuned type-I MOT. The setup can readily be transferred to any other systems working with Rb.
我们利用铷的红失谐和蓝失谐磁光阱（MOT），这得益于简化的装置以及基于液晶可变延迟器（LCVR）的新颖方法。为了在从红失谐MOT切换到蓝失谐MOT时保持捕获力，冷却光束圆偏振的旋向需要反转。LCVR允许快速的偏振控制，并且是紧凑、简单且经济高效的组件，可以很容易地在现有的激光系统中实现。通过这种方式，我们实现了一个用于8.7×10个铷原子的蓝失谐II型MOT，其亚多普勒温度为44μK，远低于传统铷I型MOT所达到的温度。与标准的红失谐I型MOT相比，相空间密度增加了两个多数量级。该装置可以很容易地转移到任何其他使用铷的系统中。
