Magnetic Feshbach resonances in ultracold atom-molecule collisions

TL;DR

This study performs precise quantum scattering calculations to investigate magnetic Feshbach resonances in ultracold atom-molecule collisions, revealing unique broad and narrow resonances influenced by spin interactions.

Contribution

It provides the first detailed numerical analysis of Feshbach resonances in ultracold atom-molecule collisions using advanced ab initio potentials, highlighting the role of spin interactions.

Findings

Broad resonances mediated by spin-exchange interactions.

Narrow resonances due to spin-rotation interactions.

Resonance density comparable to atomic collisions despite molecular states.

Abstract

We report numerically exact quantum scattering calculations on magnetic Feshbach resonances in ultracold, strongly anisotropic atom-molecule [Rb($^2$S) + SrF($^2\Sigma^+$)] collisions based on state-of-the-art ab initio potential energy surfaces. We find broad resonances mediated by the intermolecular spin-exchange interaction, as well as narrow resonances due to the intramolecular spin-rotation interaction, which are unique to atom-molecule collisions. Remarkably, the density of resonances in atom-molecule collisions is not much higher than that in atomic collisions despite the presence of a dense manifold of molecular rotational states, which can be rationalized by analyzing the adiabatic states of the collision complex.