Bose-Einstein condensation of potassium atoms by sympathetic cooling

We report on the Bose-Einstein condensation of potassium atoms, whereby qua ntum degeneracy is achieved by sympathetic cooling with evaporativety coole d rubidium. Because of the rapid thermalization of the two different atoms, the efficiency of the cooling process is high. The ability to achieve cond ensation by sympathetic cooling with a different species may provide a rout e to the production of degenerate systems with a larger choice of component s.