⁸⁵Rb tunable-interaction Bose–Einstein condensate machine

Abstract

We describe our experimental setup for creating stable Bose-Einstein condensates (BECs) of ⁸⁵Rb with tunable interparticle interactions. We use sympathetic cooling with ⁸⁷Rb in two stages, initially in a tight Ioffe-Pritchard magnetic trap and subsequently in a weak, large-volume, crossed optical dipole trap, using the 155 G Feshbach resonance to manipulate the elastic and inelastic scattering properties of the ⁸⁵Rb atoms. Typical ⁸⁵Rb condensates contain 4 x 10⁴ atoms with a scattering length of a=+200a(0). Many aspects of the design presented here could be adapted to other dual-species BEC machines, including those involving degenerate Fermi-Bose mixtures. Our minimalist apparatus is well suited to experiments on dual-species and spinor Rb condensates, and has several simplifications over the ⁸⁵Rb BEC machine at JILA, which we discuss at the end of this article. Show more