Resonantly Interacting Fermi-Fermi Mixture of $^{161}$Dy and $^{40}$K

TL;DR

This paper reports the creation of a stable ultracold Fermi-Fermi mixture of $^{161}$Dy and $^{40}$K with a broad Feshbach resonance, enabling exploration of strongly correlated fermionic states with mass imbalance.

Contribution

It demonstrates the realization of a mass-imbalanced, tunable, and collisional-stable ultracold Fermi-Fermi mixture with a broad Feshbach resonance at 217 G.

Findings

Identification of a broad Feshbach resonance at 217 G.

Observation of bimodal hydrodynamic expansion due to mass imbalance.

Significant suppression of inelastic processes on resonance.

Abstract

We report on the realization of a Fermi-Fermi mixture of ultracold atoms that combines mass imbalance, tunability, and collisional stability. In an optically trapped sample of $^{161}$Dy and $^{40}$K, we identify a broad Feshbach resonance centered at a magnetic field of $217\,$G. Hydrodynamic expansion profiles in the resonant interaction regime reveal a bimodal behavior resulting from mass imbalance. Lifetime studies on resonance show a suppression of inelastic few-body processes by orders of magnitude, which we interpret as a consequence of the fermionic nature of our system. The resonant mixture opens up intriguing perspectives for studies on novel states of strongly correlated fermions with mass imbalance.