Ultracold spin-polarized mixtures of 2Sigma molecules with S-state atoms: Collisional stability and implications for sympathetic cooling

TL;DR

This study demonstrates that low-temperature collisions between CaH molecules and alkali-metal atoms have slow inelastic spin relaxation rates, suggesting feasible sympathetic cooling of polar molecules with magnetic co-trapped atoms.

Contribution

The paper provides rigorous quantum scattering calculations showing unexpectedly slow spin relaxation, challenging prior assumptions about cooling polar molecules with alkali-metal atoms.

Findings

Inelastic spin relaxation rates are slow despite anisotropic interactions.

Results suggest sympathetic cooling of 2Sigma molecules is feasible.

Multichannel quantum defect theory explains the slow relaxation.

Abstract

The prospects of sympathetic cooling of polar molecules with magnetically co-trapped alkali-metal atoms are generally considered poor due to strongly anisotropic atom-molecule interactions leading to large spin relaxation rates. Using rigorous quantum scattering calculations based on ab initio interaction potentials, we show that inelastic spin relaxation in low-temperature collisions of CaH(2Sigma) molecules with Li and Mg atoms occurs at a slow rate despite the strongly anisotropic interactions. This unexpected result, which we rationalize using multichannel quantum defect theory, opens up the possibility of sympathetic cooling of polar 2Sigma molecules with alkali-metal and alkaline-earth atoms in a magnetic trap.