Pathway to magneto-optical trapping of SrOH for beyond-Standard Model searches

The complex structure of polyatomic molecules offers powerful features that can be exploited for applications in quantum simulation and precision measurement. One of these features is a plethora of ro-vibrational states. In the linear triatomic molecule SrOH, two vibrational states have a near-degeneracy that can be probed with microwaves (in contrast to typical vibrational splittings of ∼10 THz). Because the energies of these states depend differently on the proton-to-electron mass ratio, μ, a microwave resonance between them is highly sensitive to changes in μ over time. We report on high-resolution vibrational branching ratio measurements of four excited vibronic states. We are now able to design a laser-cooling scheme with over 10,000 photon scatters before loss to an unaddressed vibrational state, more than enough to form a MOT and load an optical trap. Only 8 lasers are required for this scheme, fewer than for any other known polyatomic molecule cooling cycle. We describe progress towards laser cooling of SrOH and a high-sensitivity measurement of μ variation using ultracold SrOH molecules.