Progress towards achieving higher phase space density of trapped SrF molecules

Recently, there has been tremendous progress in laser cooling of molecules with temperatures as low as 5µK being reported. The next natural step to increasing the phase space density is to load the molecules in a conservative trap. Here we report on our progress towards optical dipole trapping (ODT) of SrF molecules along with plans for future improvements to the apparatus. By optimizing both the polarization of the ODT light and the relative intensity imbalance of the counter-propagating beams that we use for Λ-enhanced gray molasses, we are able to load molecules with temperatures as low as 10µK in a 420µK deep trap. We also detail further improvements to the apparatus including plans for switching to a Sr + SF6 source and a better slowing scheme. With these improvements, along with the already demonstrated capability to achieve cold temperatures in deep traps, studying SrF-SrF molecule collisions should be within reach.

The authors acknowledge support from AFOSR and the Yale Quantum Institute.