Observation of magnetically tunable Feshbach resonances in ultracold $^{23}$Na$^{40}$K+$^{40}$K collisions

TL;DR

This paper reports the first observation of magnetically tunable Feshbach resonances in ultracold collisions between $^{23}$Na$^{40}$K molecules and $^{40}$K atoms, revealing detailed insights into three-body interactions at ultralow temperatures.

Contribution

It provides the first experimental detection of atom-molecule Feshbach resonances in heavy molecules, enhancing understanding of ultracold collision dynamics and three-body potential energy surfaces.

Findings

Observed three Feshbach resonances near 101 G

Resonance widths are a few hundred milliGauss

Resonances enhance loss rates, indicating strong atom-molecule interactions

Abstract

Resonances in ultracold collisions involving heavy molecules are difficult to understand, and have proven challenging to detect. Here we report the observation of magnetically tunable Feshbach resonances in ultracold collisions between $^{23}$Na$^{40}$K molecules in the rovibrational ground state and $^{40}$K atoms. We prepare the atoms and molecules in various hyperfine levels of their ground states and observe the loss of molecules as a function of the magnetic field. The atom-molecule Feshbach resonances are identified by observing an enhancement of the loss rate coefficients. We have observed three resonances at approximately 101 G in various atom-molecule scattering channels, with the widths being a few hundred milliGauss. The observed atom-molecule Feshbach resonances at ultralow temperatures probe the three-body potential energy surface with an unprecedented resolution. Our work will help to improve the understanding of complicated ultracold collisions, and open up the possibility of creating ultracold triatomic molecules.