Molecule trapping in a buffer-gas-loaded optical dipole trap: a platform for future precision measurements*

Access to cold, trapped molecules has already led to improved precision measurements of the electron’s electric dipole moment [1], molecular spectra [2], and other physical quantities. It is widely anticipated that developments in molecule trapping will lead to further progress in precision physics. To this end, we describe here a platform for trapping a wide range of small, chemically stable molecules in their absolute ground state [3]. 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. This work identifies some potential applications of this trap in the context of precision measurements, including a discussion of the impact of the high-intensity light on some measurements. Additionally, we outline the experimental progress made towards realization of such a trap, including the development of robust high-intensity optical cavities, and a novel buffer-gas cell design optimized for loading the trap.

[1] Tanya S. Roussy et al., An improved bound on the electron’s electric dipole moment. Science381,46-50(2023).

[2] K. H. Leung et al., Terahertz Vibrational Molecular Clock with Systematic Uncertainty at the 10^-14 level. Phys. Rev. X 13, 011047 – Published 28 March 2023

[3] Ashwin Singh et al., Dynamics of a buffer-gas-loaded, deep optical trap for molecules. Phys. Rev. Research 5, 033008 – Published 5 July 2023