Sub-Doppler Cooling of Cesium Atoms with Raman Gray Molasses on the D₂ Line
Ya-Fen Hsiao1,2*, Wei-Kuo Li3, Ying-Cheng Chen1
1Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
2Molecular Science and Technology, Taiwan International Graduate Program, Academia Sinica and National Central University, Taipei, Taiwan
3Department of Physics, National Taiwan University, Taipei, Taiwan
* Presenter:Ya-Fen Hsiao,
In recent years, alkali lithium and potassium atoms, which were thought to be difficult to implement the sub-Doppler cooling, have been cooled to a few tens of µK using Raman gray molasses cooling [1-4]. Although it is relatively easy to laser cool cesium to µK regime either using polarization gradient cooling or degenerate Raman sideband cooling, we experimentally investigate the Λ-enhanced sub-Doppler cooling of cesium by Raman gray molasses which is relatively easy to implement just based on the trapping and repumping lasers with suitable frequency control. In the preliminary run, we have cool down¹³³Cs atoms to 16 µK while capturing atoms of nearly 2x10⁸. We are performing a systematic study to achieve the minimum temperature by using the different hyperfine transitions, by varying the intensity ratio of the trapping and repumping lasers, by varying the one-photon and two-photon detunings of the cooling lasers under the Raman gray molasses phase, etc. The results will be presented and discussed.

Keywords: gray molasses cooling, sub-Doppler cooling