Quantum degenerate two-species Fermi-Fermi mixture coexisting with a Bose-Einstein condensate

Abstract

We report on the generation of a quantum degenerate Fermi-Fermi mixture of two different atomic species. The quantum degenerate mixture is realized employing sympathetic cooling of fermionic Li6 and K40 gases by an evaporatively cooled bosonic Rb87 gas. We describe the combination of trapping and cooling methods that proved crucial to successfully cool the mixture. In particular, we study the last part of the cooling process and show that the efficiency of sympathetic cooling of the Li6 gas by Rb87 is increased by the presence of K40 through catalytic cooling. Because of the differing physical properties of the two components, the quantum degenerate Li6-K40 Fermi-Fermi mixture is an excellent candidate for a stable, heteronuclear system allowing the study of several so far unexplored types of quantum matter. © 2008 The American Physical Society.