Feshbach spectroscopy of a K-Rb atomic mixture

TL;DR

This paper reports extensive Feshbach spectroscopy of ultracold 40K-87Rb mixtures, accurately determining interspecies scattering lengths and resonance positions to guide future experiments.

Contribution

It introduces a quantum collision model based on 14 measured resonances to predict collisional parameters for all K-Rb isotopic pairs, including scattering lengths.

Findings

Interspecies s-wave scattering lengths for 40K-87Rb determined as -111 and -215 Bohr.

14 interspecies Feshbach resonances identified and used to model collisional behavior.

Predictions made for other K-Rb isotopic pairs' scattering lengths and resonance positions.

Abstract

We perform extensive magnetic Feshbach spectroscopy of an ultracold mixture of fermionic 40K and bosonic 87Rb atoms. The magnetic-field locations of 14 interspecies resonances is used to construct a quantum collision model able to predict accurate collisional parameters for all K-Rb isotopic pairs. In particular we determine the interspecies s-wave singlet and triplet scattering lengths for the 40K-87Rb mixture as -111 +/- 5 Bohr and -215 +/- 10 Bohr respectively. We also predict accurate scattering lengths and position of Feshbach resonances for the other K-Rb isotopic pairs. We discuss the consequences of our results for current and future experiments with ultracold K-Rb mixtures.