Association of ultracold double-species bosonic molecules

TL;DR

This paper reports the creation and characterization of heterospecies bosonic molecules from ultracold 41K and 87Rb atoms, providing insights into their binding energies and association spectra, advancing the path toward Bose-Einstein condensates of dipolar molecules.

Contribution

It demonstrates the formation of heterospecies bosonic molecules via Feshbach resonances and develops a model to describe the association process, enhancing understanding of ultracold molecular systems.

Findings

Measured binding energies versus Feshbach field

Observed broadening and asymmetry in association spectra

Developed a quantitative model for association process

Abstract

We report on the creation of heterospecies bosonic molecules, associated from an ultracold Bose-Bose mixture of 41K and 87Rb, by using a resonantly modulated magnetic field close to two Feshbach resonances. We measure the binding energy of the weakly bound molecular states versus the Feshbach field and compare our results to theoretical predictions. We observe the broadening and asymmetry of the association spectrum due to thermal distribution of the atoms, and a frequency shift occurring when the binding energy depends nonlinearly on the Feshbach field. A simple model is developed to quantitatively describe the association process. Our work marks an important step forward in the experimental route towards Bose-Einstein condensates of dipolar molecules.