Detailseite
Projekt
Critical Properties of Bose-Einstein Condensates
Antragsteller
Professor Dr. Hagen Kleinert
Fachliche Zuordnung
Optik, Quantenoptik und Physik der Atome, Moleküle und Plasmen
Förderung
Förderung von 2003 bis 2007
Projektkennung
Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 5407417
The goal of the project is to understand the critical properties of homogeneous Bose-Einstein condensates above and, especially, below the critical point by applying field-theoretic methods of many-body physics. In both regimes we shall analyze the effect of an arbitrarily weak repulsive two-particle interaction on the critical temperature and the specific heat. Furthermore, below the transition, we want to investigate the influence of phase fluctuations upon the superfluid properties of homogeneous Bose-Einstein condensates. The same field-theoretic methods will then be applied to Bose-Einstein condensates trapped in optical lattices. There the periodicity leads to a quasi-free behavior due to Bloch´s theorem. In the lattice systems one can increase the effective repulsive interaction between the bosons which leads to a state with uncorrelated phases behaving like a Mott insulator. In the neighborhood of any of these transitions, perturbation expansions of physical quantities suffer from ubiquitous infrared divergencies so that the effective expansion parameter becomes infinite. We master this problem with the help of variational perturbation theory, a method developed recently in our group to determine the strong-coupling limit of divergent weak-coupling expansions.
DFG-Verfahren
Schwerpunktprogramme
Beteiligte Person
Privatdozent Dr. Axel Pelster
