Condensed Matter Physics Seminar

Trapped dipolar Bose-Einstein condensates

Prof. Duncan O'Dell
McMaster University

Time
Thu. November 22, 2007     10:30 AM     STI 501

Abstract

The atoms in conventional atomic Bose-Einstein condensates interact via short-range isotropic interactions (van der Waals interactions). However, recently a BEC of chromium atoms was made by Pfau's group in Stuttgart [PRL 94, 160401 (2005)]. Chromium has an anomalously large magnetic dipole moment and consequently a chromium BEC has significant dipole-dipole interactions. There are also many efforts going on worldwide to make ultracold polar molecules which have potentially huge dipole moments. In this talk I will introduce the theory of trapped dipolar condensates and compare it to the results of experiments conducted so far. We shall see how the long-range and anisotropic form of the dipole-dipole interaction leads to new mesoscopic effects which depend on the shape of the condensate surface. These include magnetotstriction and the appearance of a `roton' minimum in the excitation spectrum. Finally, I will discuss dipolar BECs in rotating traps and indicate how the shape of the BEC surface determines its rotational properties.

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