Understanding the production of dual Bose-Einstein condensation with sympathetic cooling - art. no. 051602

We show, both experimentally and theoretically, that sympathetic cooling of Rb-87 atoms in the \F = 2,m(F) = 2 > state by evaporatively cooled atoms i n the \F = 1,m(F) = -1 > state can be precisely controlled so as to produce a condensate in either or both states. We also study the thermalization ra te between two species. Our model renders a quantitative account of the obs erved role of the overlap between the two clouds and verifies that sympathe tic cooling becomes inefficient when the masses are very different. Our cal culation also yields an analytical expression of the thermalization rate fo r a single species.