Coherent molecule formation in anharmonic potentials near confinement-induced resonances

TL;DR

This paper investigates how anharmonic trapping potentials enable coherent molecule formation from ultracold atom pairs, revealing the significant impact of center-of-mass and relative motion coupling in quasi-1D quantum systems through combined theoretical and experimental analysis.

Contribution

It demonstrates the first direct observation of coherent molecule formation caused by anharmonicity-induced coupling in a two-atom system, with quantitative agreement between theory and experiment.

Findings

Coherent molecule formation observed in two-atom systems.

Anharmonicity couples center-of-mass and relative motion.

Theoretical predictions match experimental results.

Abstract

We perform a theoretical and experimental study of a system of two ultracold atoms with tunable interaction in an elongated trapping potential. We show that the coupling of center-of-mass and relative motion due to an anharmonicity of the trapping potential leads to a coherent coupling of a state of an unbound atom pair and a molecule with a center of mass excitation. By performing the experiment with exactly two particles we exclude three-body losses and can therefore directly observe coherent molecule formation. We find quantitative agreement between our theory of inelastic confinement-induced resonances and the experimental results. This shows that the effects of center-of-mass to relative motion coupling can have a significant impact on the physics of quasi-1D quantum systems.