Dysprosium dipolar Bose-Einstein condensate with broad Feshbach resonances

Abstract

We produce Bose-Einstein condensates of $^{162}\mathrm{Dy}$ atoms employing an innovative technique based on a resonator-enhanced optical trap that allows efficient loading from the magneto-optical trap. We characterize the scattering properties of the ultracold atoms for magnetic fields between 6 and 30 G. In addition to the typical chaotic distribution of narrow Feshbach resonances in lanthanides, we discover two rather isolated broad features at around 22 G and 27 G. A characterization using the complementary measurements of losses, thermalization, anisotropic expansion, and molecular binding energy points towards resonances of predominant $s$-wave character. Such resonances will ease the investigation of quantum phenomena relying on the interplay between dipole and contact interactions.