Universal three-body physics in ultracold KRb mixtures

TL;DR

This study investigates three-body interactions in ultracold heteronuclear potassium-rubidium mixtures, finding universal behavior consistent with theoretical models and no Efimov resonances within accessible scattering lengths.

Contribution

The paper provides the first systematic measurement of three-body recombination in K-Rb mixtures, confirming universality and aligning with theoretical predictions.

Findings

No Efimov resonances observed in the mixtures.

Results agree with the theoretical scattering-dependent recombination model.

Universality is reestablished across isotopic mixtures.

Abstract

Ultracold atomic gases have recently become a driving force in few-body physics due to the observation of the Efimov effect. While initially observed in equal mass systems, one expects even richer few-body physics in the heteronuclear case. In previous experiments with ultracold mixtures of potassium and rubidium, an unexpected non-universal behavior of Efimov resonances was observed. In contrast, we measure the scattering length dependent three-body recombination coefficient in ultracold heteronuclear mixtures of $^{39}\mathrm{K}$-\87Rb and $^{41}\mathrm{K}$-\87Rb and do not observe any signatures of Efimov resonances for accessible scattering lengths in either mixture. Our results show good agreement with our theoretical model for the scattering dependent three-body recombination coefficient and reestablish universality across isotopic mixtures.