Large molasses-like cooling forces for molecules using polychromatic optical fields: A theoretical description

TL;DR

This paper presents a theoretical framework for using polychromatic optical fields to generate large molasses-like cooling forces in complex molecules, potentially enabling advanced quantum control and higher densities in molecular cooling.

Contribution

It introduces a novel configuration for Suppressed Emission Rate (SupER) molasses using polychromatic fields addressing multiple electronic transitions, applicable to complex polyatomic molecules.

Findings

Feasible creation of SupER molasses with large capture velocities (~40 m/s)

Numerical and Monte Carlo simulations support the approach's effectiveness

Potential to extend laser cooling to complex molecules with vibrational decay channels

Abstract

Recent theoretical investigations have indicated that rapid optical cycling should be feasible in complex polyatomic molecules with diverse constituents, geometries and symmetries. However, as a composite molecular mass grows, so does the required number of photon scattering events necessary to decelerate and confine molecular beams using laser light. Utilizing coherent momentum exchange between light fields and molecules can suppress spontaneous emission and significantly reduce experimental complexity for slowing and trapping. Working with BaH as a test species, we have identified a robust, experimentally viable configuration to achieve large molasses-like cooling forces for molecules using polychromatic optical fields addressing both $X-A$ and $X-B$ electronic transitions, simultaneously. Using numerical solutions of the time-dependent density matrix as well as Monte Carlo simulations, we demonstrate that creation of Suppressed Emission Rate (SupER) molasses with large capture velocities ($\sim 40$ m/s) is generically feasible for polyatomic molecules of increasing complexity that have an optical cycling center. Proposed SupER molasses are anticipated to not only extend quantum control to novel molecular species with abundant vibrational decay channels, but also significantly increase trapped densities for previously laser-cooled diatomic and triatomic species.