A mixture of Bose and Fermi superfluids

Abstract

Making a superfluid lithium mixture: At some of the coldest temperatures achieved in the laboratory, researchers can coax dilute gases of atoms into becoming a superfluid, with the whole gas behaving as one entity. Bosonic atoms, which like to congregate in one state, achieve this willingly. Fermions, which effectively repel each other, require more persuasion. Ferrier-Barbut et al. made a superfluid mixture of two gases, one made up of bosons and one of fermions. They used two isotopes of lithium, fermionic ⁶ Li and bosonic ⁷ Li. When they made the mixture oscillate, the two components took turns feeding energy into each other. Science , this issue p. 1035