Studying a dualspecies BEC with tunable interactions.pdfVIP

Studying a dual-species BEC with tunable interactions S. B. Papp,1, ∗ J. M. Pino,1 and C. E. Wieman2, 1 1JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA 2 University of British Columbia, Vancouver, BC V6T 1Z1, CANADA (Dated: February 19, 2008) We report on the observation of controllable spatial separation in a dual-species Bose-Einstein condensate (BEC) with 85Rb and 87Rb. Interparticle interactions between the different components can change the miscibility of the two quantum fluids. In our experiments, we clearly observe the 8 immiscible nature of the two simultaneously Bose-condensed species via their spatial separation. 0 Furthermore the 85Rb Feshbach resonance near 155 G is used to change them between miscible 0 and immiscible by tuning the 85Rb scattering length. Our apparatus is also able to create 85Rb 2 condensates with up to 8 ×104 atoms which represents a significant improvement over previous work. b e F Two-component quantum fluids have long been known ids, and a route to dual-species BEC with Rb was pro- 9 to exhibit rich physics that is not accessible in a sim- posed in Ref. [19]. The tendency for spatial separation 1 ple single-component fluid [1]. The miscibility of two to occur in a 85Rb –87Rb mixture can be predicted by ] quantum fluids represents a fundamental property of a applying the theoretical analys