title: Atomic gases at negative kinetic temperature.
abstract: We show that thermalization of the motion of atoms at negative temperature is possible in an optical lattice, for conditions that are feasible in current experiments. We present a method for reversibly inverting the temperature of a trapped gas. Moreover, a negative-temperature ensemble can be cooled (reducing |T|) by evaporation of the lowest-energy particles. This enables the attainment of the Bose-Einstein condensation phase transition at negative temperature.
authors.affiliation: Department of Science & Technology, University of Twente, AE Enschede, The Netherlands.
authors.forename: A P
authors.initials: AP
authors.lastname: Mosk