Fermion mediated pairing in a Cs-Li Bose-Fermi mixture*

The unique control and tunability of ultracold atomic Bose-Fermi mixtures makes them a powerful testbed for simulating quantum mechanics, from few-body problems such as the Efimov effect (originally predicted in a nuclear physics context), to many-body systems such as the RKKY interaction (originally predicted in a solid-state context). In our ⁶Li-¹³³Cs system, we have observed both of these phenomena in different limits. The Efimov effect was studied at low densities and strong interactions, and the RKKY effect at quantum degeneracy and weak interactions. In this work, we study the behavior of the mixture near an interspecies Feshbach resonance, attempting to connect the two limits. We observe an effective boson-boson resonance induced by the Fermi gas, and compare our observations to theoretical predictions.