Observation of low-field Feshbach resonances between $^{161}$Dy and $^{40}$K

TL;DR

This paper reports the observation and characterization of low-field Feshbach resonances in a $^{161}$Dy-$^{40}$K mixture, enabling tunable interactions, molecule formation, and potential studies of mass-imbalanced superfluids.

Contribution

It presents the first observation of low-field Feshbach resonances in a Dy-K mixture, with detailed characterization and demonstration of molecular formation and hydrodynamic behavior.

Findings

Five Feshbach resonances characterized by thermalization and binding energy measurements.

Achieved lifetimes of several hundred milliseconds for resonantly interacting mixtures.

Demonstrated hydrodynamic expansion and DyK molecule formation.

Abstract

We report on the observation of Feshbach resonances at low magnetic field strength (below 10 G) in the Fermi-Fermi mixture of $^{161}$Dy and $^{40}$K. We characterize five resonances by measurements of interspecies thermalization rates and molecular binding energies. As a case of particular interest for applications, we consider a resonance near 7.29 G, which combines accurate magnetic tunability and access to the universal regime of interactions with experimental simplicity. We show that lifetimes of a few 100 ms can be achieved for the optically trapped, resonantly interacting mixture. We also demonstrate the hydrodynamic expansion of the mixture in the strongly interacting regime and the formation of DyK Feshbach molecules. Our work opens up new experimental possibilities in view of mass-imbalanced superfluids and related phenomena.