Improved Optical Trapping of SrOH to Probe Ultralight Dark Matter

Abstract

Polyatomic molecules are promising platforms for conducting precision measurements to probe the Standard Model, owing to their unique degrees of freedom including vibrations and rotations. In particular, ultracold SrOH has sensitivity to the variation of the proton to electron mass ratio $\mu$ and subsequently to scalar ultralight dark matter (UDM) fields. We discuss the laser slowing, sub-Doppler cooling, and trapping of SrOH and present an order of magnitude improved trap number through the use of transverse cooling of the molecular beam resulting in $\sim$$10^4$ optically trapped molecules. This would allow for a two order of magnitude improvement on the current best sensitivities to UDM over four decades of mass. Probing $\mu$-variation is not only important for UDM studies, but has more general implications for a variety of fundamental physics searches. Additionally, this increase in trapped molecule number makes SrOH a viable candidate in the search for the electron's electric dipole moment ($e$EDM) for fundamental symmetry violations. These techniques are broadly applicable, and make cooling and trapping heavier and more complex molecules with greater sensitivity to fundamental physics more viable.