A Bose-Einstein condensate of metastable atoms

We report the realization of a Bose-Einstein condensate of metastable atoms (helium in the Lowest triplet state). The excitation energy of each atom w ith respect to the ground state is 20 electron volts, but inelastic process es that would destroy the sample are suppressed strongly enough in a spin-p olarized sample to allow condensation. Our detection scheme takes advantage of the metastability to achieve detection of individual atoms as well as o f the decay products of inelastic processes. This detection opens the way t oward new studies in mesoscopic quantum statistical physics, as well as in atomic quantum optics.