Prospects for sympathetic cooling of molecules in electrostatic, ac and microwave traps

TL;DR

This paper investigates the potential for sympathetic cooling of molecules using ultracold atoms in various traps, finding microwave traps most promising due to minimal inelastic losses.

Contribution

It provides the first detailed analysis of sympathetic cooling feasibility for LiH molecules with ultracold Li atoms across different trapping methods.

Findings

Inelastic losses prevent cooling in static traps.

AC traps cause trap loss due to collision-induced trajectory changes.

Microwave traps enable sympathetic cooling without significant losses.

Abstract

We consider how trapped molecules can be sympathetically cooled by ultracold atoms. As a prototypical system, we study LiH molecules co-trapped with ultracold Li atoms. We calculate the elastic and inelastic collision cross sections of LiH + Li with the molecules initially in the ground state and in the first rotationally excited state. We then use these cross sections to simulate sympathetic cooling in a static electric trap, an ac electric trap, and a microwave trap. In the static trap we find that inelastic losses are too great for cooling to be feasible for this system. The ac and microwave traps confine ground-state molecules, and so inelastic losses are suppressed. However, collisions in the ac trap can take molecules from stable trajectories to unstable ones and so sympathetic cooling is accompanied by trap loss. In the microwave trap there are no such losses and sympathetic cooling should be possible.