Trapping Fermionic ${}^{40}$K and Bosonic ${}^{87}$Rb on a Chip

Abstract

We demonstrate the loading of a Bose-Fermi mixture into a microfabricated magnetic trap. In a single-chamber vacuum system, laser-cooled atoms are transported to the surface of a substrate on which gold wires have been microfabricated. The magnetic field minimum formed near these current-carrying wires is used to confine up to $6\times 10^4$ neutral ${}^{40}$K atoms. In addition, we can simultaneously load $2\times 10^5$ ${}^{87}$Rb atoms, demonstrating the confinement of two distinct elements with such a trap. In a sequence optimized for ${}^{87}$Rb alone, we observe up to $1\times 10^7$ trapped atoms. We describe in detail the experimental apparatus, and discuss prospects for evaporative cooling towards quantum degeneracy in both species.

10 pages, 6 figures. To appear in Journal of Low Temperature Physics, Vol 140, Nos. 5/6, September 2005. (v4: proof corrections, references updated.)