Feshbach Loss Spectroscopy in an Ultracold $^{23}$Na and $^{40}$K Mixture

TL;DR

This study reports the discovery of 24 new interspecies Feshbach resonances in an ultracold $^{23}$Na and $^{40}$K mixture, including 12 d-wave resonances, and refines theoretical models for better agreement with experimental data.

Contribution

The paper provides the first comprehensive Feshbach spectroscopy in Na-K mixtures and improves the Born-Oppenheimer potentials based on new experimental data.

Findings

24 new interspecies Feshbach resonances observed

12 d-wave Feshbach resonances identified

Refined theoretical potentials match experimental results

Abstract

We perform Feshbach spectroscopy in an ultracold mixture of $^{23}$Na and $^{40}$K with different spin-state combinations. We have observed 24 new interspecies Feshbach resonances at magnetic field up to 350 G. A full coupled-channel calculation is performed to assign these resonances. Among them, 12 resonances are identified as d-wave Feshbach resonances. These d-wave Feshbach resonances are about 5 G systematically smaller than the predications based on previous model potential. Taking into account these new experimental results, we improve the Born-Oppenheimer potentials between Na and K, and achieve good agreement between the theory and experiment for all the observed Feshbach resonances.