The “chip” experiment is a compact degenerate Fermi-gas machine. Each experimental cycle begins by laser cooling both Rubidium 87 and Potassium 40, and then trapping both species magnetically.

A micofabricated electromagnet compresses the mixture, and allows evaporatively cooled 87Rb, a boson, to act as a cooland for 40K, a fermion. Finally, quantum degeneracy is achieved in a purely optical trap. From this starting point, we have pursued several lines of investigation: (1) the physics of gases whose interactions are unitary, meaning that collisions are as strong as allowed by quantum mechanics; (2) universal relations that emerge from the strength of short-range correlations;  (3) pairs of 40K atoms with p-wave orbital wave functions; and (4) non-equilibrium phenomena, such as a transition between dynamical phases.

Team :  C. J. Dale, K. G. S. Xie, K. Pond Grehan, M. Wang