München 2004 – wissenschaftliches Programm
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Q: Quantenoptik und Photonik
Q 18: Quantengase II
Q 18.7: Vortrag
Dienstag, 23. März 2004, 12:30–12:45, HS 225
Quantum Phase Diagram for Bose Gases — •Axel Pelster1, Hagen Kleinert1, and Sebastian Schmidt2 — 1Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany — 2Department of Physics, Yale University, P.O. Box 208120, New Haven, CT 06520-8120, USA
We locate the quantum phase transition for a dilute homogeneous Bose gas in the plane of s-wave scattering length as and temperature T. This is done by improving a lowest-order result for the thermodynamic potential with the help of recent high-order perturbative calculations on the leading shift of the critical temperature due to a weak atomic repulsion using variational perturbation theory. The quantum phase diagram shows a nose above the interaction-free critical temperature Tc(0), so that we predict the existence of a reentrant transition above Tc(0), where an increasing repulsion leads to the formation of a condensate. Furthermore, we obtain a similar quantum phase diagram for a bose gas trapped in an optical lattice as a function of effective scattering length aeff and temperature T.
[1] H. Kleinert, S. Schmidt, and A. Pelster, cond-mat/0307412