Trapping Fermionic ⁴⁰K and Bosonic ⁸⁷Rb on a Chip

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 $6\times10^4$ 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.