Mainz 2017 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 29: Quantum Gases: Bosons IV
Q 29.8: Vortrag
Dienstag, 7. März 2017, 16:15–16:30, P 204
Dimensionally Induced Phase Transition of the Weakly Interacting Ultracold Bose Gas — •Bernhard Irsigler1,2 and Axel Pelster3 — 1Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, Germany — 2Institut für Theoretische Physik, Freie Universität Berlin, Germany — 3Fachbereich Physik und Forschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Germany
We investigate the dimensionally induced phase transition from the normal to the Bose-Einstein condensed phase for a weakly interacting Bose gas in optical lattices. To this end we make use of the Hartree-Fock-Bogoliubov-Popov theory, where we include numerically exact hopping energies and effective interaction strengths. At first we determine the critical chemical potential, where we find a much better agreement with recent experimental data than a pure Hartree-Fock treatment [1]. We ascribe this finding to the dominant role of quantum fluctuations in lower dimensions. Furthermore, we determine for the 1D-3D-transition the power-law exponent of the critical temperature for two different non-interacting Bose gas models yielding the same exponent of 1/2 which indicates that they belong to the same universality class. For the weakly interacting Bose gas we find for both models that this exponent is robust with respect to finite interaction strengths.
[1] A. Vogler, R. Labouvie, G. Barontini, S. Eggert, V. Guarrera, and H. Ott, Phys. Rev. Lett. 113, 215301 (2014)