Heteronuclear molecules in an optical dipole trap

Abstract

We report on the creation and characterization of heteronuclear $^{40}\text{K}^{87}\text{R}\text{b}$ Feshbach molecules in an optical dipole trap. Starting from an ultracold gas mixture of $^{40}\text{K}$ and $^{87}\text{R}\text{b}$ atoms, we create as many as 25 000 molecules at 300 nK by rf association. Optimizing the association process, we achieve a conversion efficiency of 25%. We measure the temperature dependence of the rf association process and find good agreement with a phenomenological model that has previously been applied to Feshbach molecule creation by slow magnetic-field sweeps. We also present a measurement of the binding energy of the heteronuclear molecules in the vicinity of the Feshbach resonance and provide evidence for Feshbach molecules as deeply bound as 26 MHz.