Experiments with a two-species Bose-Einstein condensate utilizing widely tunable interparticle interactions

Carl Wieman

Scott B. Papp, Pino, J. M., Carl Wieman

We report on the observation of controllable spatial separation in a dual-species Bose-Einstein condensate (BEC) with $^{85}$Rb and $^{87}$Rb. Interparticle interactions between the different components can change the miscibility of the two quantum fluids. In our experiments, we clearly observe the immiscible nature of the two simultaneously Bose-condensed species via their spatial separation. Furthermore the $^{85}$Rb Feshbach resonance near 155 G is used to change them between miscible and immiscible by tuning the $^{85}$Rb scattering length. Our apparatus is also able to create $^{85}$Rb condensates with up to $8\times10^4$ atoms which represents a significant improvement over previous work.

E. Arimondo

P. A. Altin, Nicholas P. Robins, D. Döring +4 more

We describe our experimental setup for creating stable Bose-Einstein condensates (BECs) of (85)Rb with tunable interparticle interactions. We use sympathetic cooling with (87)Rb 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 (85)Rb atoms. Typical (85)Rb condensates contain 4 x 10(4) 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 (85)Rb BEC machine at JILA, which we discuss at the end of this article.

G. Roati, Jacopo Catani, Chiara D’Errico +6 more

We produce a novel Bose-Einstein condensate composed of39K atoms. Condensation of this species was so far prevented by a naturally small and negative scattering length. We report on the properties of the39K Bose-Einstein condensates, and on ongoing experiments on atom interferometry.

D. Dries, Yong P. Chen, J. M. Hitchcock +4 more