Trap Holds Condensates of Two Different Spin States at Once

Everyone likes a bargain, and what could be better than two for the price of one? That's what researchers in Boulder, Colorado, must have figured when they snared not just one but two spin states of the rubidium atom in an ultracold trap and simultaneously formed overlapping Bose–Einstein condensates from them. The feat—accomplished by Eric Cornell, Carl Wieman and their colleagues at JILA, the University of Colorado and the National Institute of Standards and Technology in Boulder—gives a valuable tool to those interested in atomic collisions and their dependence on spin states, as well as to those interested in further exploration of interactions between and within condensates. As William Phillips of NIST in Gaithersburg, Maryland, points out, such a double condensate, of two different internal states of the same atom, is unlike anything seen in superfluid $He4,$ a condensed‐matter Bose–Einstein condensate.