Creation of a degenerate Bose-Bose mixture of erbium and lithium atoms

We report the realization of a degenerate mixture of ¹⁶⁶Er and ⁷Li atoms in their lowest spin state. The two species are sequentially laser-cooled and loaded into an optical dipole trap, then transported to a glass cell in which further cooling to degeneracy occurs. Since Er is more weakly trapped, it serves as a coolant for Li, and we observe efficient sympathetic cooling facilitated by a large interspecies elastic scattering cross section. Three-body losses are found to be small at the magnetic fields explored, making this platform promising for the study of interacting mixtures with large mass imbalance.