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TT: Fachverband Tiefe Temperaturen

TT 30: Matter At Low Temperature: Quantum Liquids, Bose-Einstein Condensates, Ultra-cold Atoms, ... 1

TT 30.5: Vortrag

Mittwoch, 28. März 2012, 16:15–16:30, H 3005

Ultracold atomic gases at negative absolute temperatures — •Akos Rapp — Institut f. Theoretische Physik, Leibniz Universität, Hannover, Deutchland

Ultracold atomic clouds are used to simulate a broad range of complex quantum systems with a high degree of experimental control. We will discuss that current techniques allow for a realization of an out-of-equilibrium situation where the system relaxes to a state with negative absolute temperature, T<0. Under these conditions, higher energy levels are more likely occupied than lower energy levels. As a consequence, bosonic atoms in an optical lattice condense at finite momenta, at the maxima instead of the minimum of the kinetic energy. A further interesting possibility of using T<0 is that one can experimentally reach new parameter regimes. This idea could be applied to simulate the SU(3) attractive Hubbard model with repulsively interacting atoms, which can prove useful to understand some puzzles of quantum chromodynamics.