title: Tunable miscibility in a dual-species Bose-Einstein condensate.
abstract: We report on the observation of controllable phase separation in a dual-species Bose-Einstein condensate with 85Rb and 87Rb. Interatomic interactions between the different components determine the miscibility of the two quantum fluids. In our experiments, we can clearly observe immiscible behavior via a dramatic spatial separation of the two species. Furthermore, a magnetic-field Feshbach resonance is used to change them between miscible and immiscible by tuning the 85Rb scattering length. The spatial density pattern of the immiscible quantum fluids exhibits complex alternating-domain structures that are uncharacteristic of its stationary ground state.
authors.affiliation: JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Papp
authors.forename: J M
authors.initials: JM
authors.lastname: Pino
authors.forename: C E
authors.initials: CE
authors.lastname: Wieman