Dynamics of a buffer-gas-loaded, deep optical trap for molecules

Despite a diversity of interest in studying cold molecules, access to cold, trapped molecule samples has been limited to only a few select species. To this end, we here outline the design of an experiment aimed at trapping a variety of small, closed-shell molecules, such as N₂, O₂, CO, 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 will be 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. The very far-off-resonant, quasi-electrostatic trapping mechanism is insensitive to a molecule’s internal state, energy level structure, and its electric and magnetic dipole moment. From our theoretical investigations of the trapping and loading dynamics, as well as the heating and loss rates, we conclude that 10⁴–10⁶ molecules are likely to be trapped. Our trap would open new possibilities in molecular spectroscopy, studies of cold chemical reactions, and precision measurement, amongst other fields of physics.

[1] Singh, A., Maisenbacher, L., Lin, Z., Axelrod, J., Panda, C., & Müller, H. (2023). Dynamics of a buffer-gas-loaded, deep optical trap for molecules. https://arxiv.org/abs/2301.12620