Universal three-body parameter in heteronuclear atomic systems

TL;DR

This paper predicts a universal three-body parameter in heteronuclear atomic systems near broad Feshbach resonances, extending the concept of universality from homonuclear gases to more complex mixtures, with physical explanations based on van der Waals interactions.

Contribution

It introduces the prediction of a universal three-body parameter for heteronuclear systems and explains its physical origin using a Born-Oppenheimer approach.

Findings

Universal 3BP predicted for heteronuclear systems near broad Feshbach resonances.

Physical origin of universality depends on atomic mass composition.

Numerical values provided for alkali atom combinations.

Abstract

In Efimov physics, a three-body parameter (3BP), previously regarded as nonuniversal, uniquely defines bound and scattering properties of three particles. A universal 3BP, however, have been recently shown in experiments and theory in ultracold homonuclear gases. Our present study further predicts a universal 3BP for heteronuclear atomic systems near broad Feshbach resonances, and provides physical interpretations for its origin. We show that for a system composed of two light and one heavy atoms, the physical origin of the universal 3BP is similar to the homonuclear case while for systems composed by one light and two heavy atoms the universality of the 3BP is now mostly controlled by the heavy-heavy interatomic properties. This new universality is explained by the universal properties of the van der Waals interactions in a simple Born-Oppenheimer (BO) picture. Finally, we show the numerically determined 3BPs for some combinations of alkali atoms used in ultracold experiments.