Towards a buffer-gas-loaded, multi-species optical trap for molecules

Despite much interest in studying cold molecules, access to cold, trapped molecules has been limited to only a few select species. We here present progress towards trapping a variety of small, chemically stable molecules, such as N2, CO, O2, and HCl [1]. The molecules will be trapped at cryogenic temperatures by buffer-gas loading a deep optical dipole trap. The ~10 K trap depth is produced by a tightly-focused, 1064-nm cavity capable of reaching intensities of hundreds of GW/cm². Molecules will be directly buffer-gas loaded into the trap using a helium buffer gas at 1.5 K. Both buffer-gas cooling and the very far-off-resonant, quasi-electrostatic trapping mechanism are insensitive to a molecule’s energy level structure and dipole moments, allowing for co-trapping of multiple species. Our trap would open new possibilities in molecular spectroscopy, studies of cold chemical reactions, and precision measurement, amongst other fields of physics.

We are currently constructing the first demonstration of such a trap. Here, we report on our progress and present first experimental results.

[1] A. Singh et al. “Dynamics of a Buffer-Gas-Loaded, Deep Optical Trap for Molecules.” Physical Review Research 5, 033008 (2023).