Magnetically Controlled Exchange Process in an Ultracold Atom-Dimer Mixture

TL;DR

This study observes a magnetically controlled exchange process in an ultracold atom-dimer mixture, demonstrating threshold behavior and high efficiency due to halo molecular states, with results aligning with three-body quantum calculations.

Contribution

It provides the first experimental observation of a magnetically tunable exchange process in ultracold atom-dimer systems with theoretical validation.

Findings

Exchange process is magnetically tunable from endoergic to exoergic.

Process does not cause trap loss unlike relaxation to deeper states.

Experimental results agree with three-body Schrödinger equation calculations.

Abstract

We report on the observation of an elementary exchange process in an optically trapped ultracold sample of atoms and Feshbach molecules. We can magnetically control the energetic nature of the process and tune it from endoergic to exoergic, enabling the observation of a pronounced threshold behavior. In contrast to relaxation to more deeply bound molecular states, the exchange process does not lead to trap loss. We find excellent agreement between our experimental observations and calculations based on the solutions of three-body Schr\"odinger equation in the adiabatic hyperspherical representation. The high efficiency of the exchange process is explained by the halo character of both the initial and final molecular states.