Observation of Feshbach resonances between ultracold Na and Rb atoms

TL;DR

This study reports the observation of Feshbach resonances in an ultracold mixture of sodium and rubidium atoms, enabling potential formation of stable NaRb molecules with strong dipolar interactions.

Contribution

First identification and characterization of interspecies Feshbach resonances between ultracold Na and Rb atoms, refining interaction potentials and aiding molecule formation.

Findings

Multiple s-wave and p-wave resonances observed near specific magnetic fields

Two s-wave resonances identified as candidates for molecule association

Results match coupled-channel model predictions

Abstract

We have successfully prepared an optically trapped ultracold mixture of $^{23}$Na and $^{87}$Rb atoms and studied their interspecies Feshbach resonances. Using two different spin combinations, several s-wave and p-wave resonances are identified by observing a high inelastic loss and a temperature rising for both species near resonant magnetic field values. The two s-wave resonances observed below 500 G between atoms in the lowest energy level are possible candidates for Feshbach molecule association. Our results are well characterized by a coupled-channel model and are used refining the ground state interaction potentials between $^{23}$Na and $^{87}$Rb. This work opens up the prospect for preparing ultracold ensembles of ground-state bosonic NaRb molecules which are chemically stable and can provide strong dipolar interactions.