Dresden 2011 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 3: Cold Molecules 1
Q 3.2: Vortrag
Montag, 14. März 2011, 10:45–11:00, BAR Schön
Bogoliubov Theory of Dipolar Bose-Einstein Condensates — •Aristeu R. P. Lima1 and Axel Pelster2 — 1Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2Fachbereich Physik, Universität Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg, Germany
Nowadays, Bose-Einstein condensates with a weak anisotropic and long-range dipole-dipole interaction, such as 52Cr condensates, are considered to be relatively well understood in terms of the Gross-Pitaevskii mean-field theory. Howerever, for highly magnetic atoms, such as dysprosium, or for strongly polar heteronuclear molecules, as for instance 40K-87Rb, quantum fluctuations in dipolar condensates could become relevant. To this end, we discuss at first the Lee-Huang-Yang correction to the sound velocity of a homogeneous dipolar condensate as derived from the Bogoliubov theory. In order to take the harmonic trapping potential into account, we extend our calculations with the help of the Bogoliubov-de Gennes theory. Thereby, we make use of the local density approximation to derive the Bogoliubov spectrum analytically, from which we determine then physical quantities of interest such as the condensate depletion and the quantum corrections to the low-lying excitation frequencies as well as to the time-of flight dynamics. Due to the delicate interplay between the dipolar interaction and the condensate geometry, we find that the influence of the quantum fluctuations can be strongly affected by the trap aspect ratio. Therefore, we are quite optimistic that future experiments will detect these beyond mean-field effects.