In this thesis we study various dissipative processes that are associated with the flow of an atomic Bose-Einstein condensate at zero temperature. In particular, we investigate the effect of a weak correlated disorder potential on the collective dipole
motion of a harmonically-confined elongated condensate. By using an extension of
the Harmonic Potential Theorem, we demonstrate that the dynamics of the system
can be described equivalently in terms of a disorder potential oscillating relative to
a stationary condensate. This latter point of view allows the application of linear
response theory to determine the drag force experienced by the condensate and to
evaluate the damping rate of the centre of mass oscillation. The density response
function for the elongated condensate is determined with a new local density approximation that takes into account the tight radial confinement of the atomic cloud.
Our linear response theory reveals the detailed dependence of the damping rate on
various system parameters. A comparison with available experimental data is only
partially successful and points to the need for additional experiments. In addition to
disorder induced dissipation, we also consider a variety of other problems that can
be addressed by means of linear response theory. For example, we study momentum
transferred to a condensate by a Bragg pulse and the energy absorption of a gas in an
optical lattice that is parametrically modulated in different ways. All of these applications demonstrate the utility of linear response theory in describing the dynamics of Bose-condensed systems which are subjected to weak perturbations. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2013-04-26 10:54:11.915
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/7956 |
| Date | 26 April 2013 |
| Creators | Wu, ZHIGANG |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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