85Rb tunable-interaction Bose–Einstein condensate machine

摘要

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 4×104 atoms with a scattering length of a = +200a0. 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. © 2010 American Institute of Physics Article Outline INTRODUCTION OVERVIEW VACUUM SYSTEM LASER SYSTEM MAGNETO-OPTICAL TRAPS MAGNETIC TRAP CONTROL AND IMAGING SYMPATHETIC COOLING OPTICAL DIPOLE TRAP FESHBACH MAGNETIC FIELD BOSE–EINSTEIN CONDENSATION COMPARISON CONCLUSION AND OUTLOOK