Dresden 2011 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 26: Poster III

A 26.65: Poster

Donnerstag, 17. März 2011, 16:00–18:30, P2

Single particle and bound state condensation in interacting Bose gases — •Michael Maennel1,2, Klaus Morawetz1,3, Pavel Lipavsky4,5, and Michael Schreiber21Department Physical Engineering, Münster University of Applied Science, 48565 Steinfurt, Germany — 2Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany — 3International Institute of Physics, Universidade Federal do Rio grande do Norte, 59.072-970 Natal-RN, Brazil — 4Institute of Physics, Academy of Sciences, 16253 Prague 6, Czech Republic — 5Faculty of Mathematics and Physics, Charles University, 12116 Prague 2, Czech Republic

We investigate a Bose gas with finite-range interaction using a scheme to eliminate self interaction in the T-matrix approximation. In this way the corrected T-matrix becomes suitable to calculate properties below the critical temperature, without the use of anomalous functions. We calculate the phase diagram, excitation spectrum and equation of state. For attractive interaction, an Evans-Rashid transition occurs between a quasi-ideal Bose gas and a BCS-like phase. In the latter there is a condensation of bound states resulting in a gap in the excitation spectrum. The gap decreases with increasing density and vanishes at the critical density for Bose-Einstein condensation, where the single-particle dispersion becomes linear for small momenta. The investigation of the equation of state indicates however, that the mentioned phase transitions might be inaccessible due to a preceding liquefaction.

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