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Quantum reflection of Bose-Einstein Condensates

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dc.contributor.advisor Wolfgang Ketterle and David E. Pritchard. en_US Pasquini, Thomas A., Jr en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Physics. en_US 2009-04-29T17:42:58Z 2009-04-29T17:42:58Z 2007 en_US 2007 en_US
dc.description Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2007. en_US
dc.description Includes bibliographical references (p. 133-147). en_US
dc.description.abstract Recent developments in atom optics have brought Bose-Einstein condensates within 1 pm of solid surfaces where the atom-surface interactions can no longer be ignored. At long- range, the atom-surface interaction is described by the weakly attractive Casimir-Polder potential which is classically predicted to accelerate an incident atom toward the surface where it will interact strongly with the internal modes of the surface, lose energy, and land in a bound state of the surface. When the incident atom is very cold, on the order of a few nanokelvin, however, the acceleration of the atomic wavefunction is so abrupt that the atom may partially reflect from the attractive tail in a process known as quantum reflection. This work presents experimental evidence for quantum reflection from a solid surface at normal incidence. Using atoms from a 23Na BEC, cooled to a few nanokelvin in a recently demonstrated single-coil trap, controlled collisions were induced between atoms and solid silicon surface. A maximum reflection probability of - 12% was observed for an incident velocity of 1 mm/s. Atoms confined against the surface at low density exhibited an enhanced lifetime due to quantum reflection. A surprising aspect of quantum reflection is that nano-structured surfaces are predicted to exhibit enhanced quantum reflection due to the reduction of the atom-surface interaction from reduced density surfaces. Using a pillared surface with an density reduced to 1% of bulk density, we observe an enhancement of the reflection probability to ' 60%. At velocities from 2-25 mm/s, predicted threshold dependence of the reflection probability was observed. At velocities below 2 mm/s, the reflection probability was observed to saturate. We develop a simple model which predicts the saturation as a result of mean-field interactions between atoms in the incident Bose-Einstein condensate. en_US
dc.description.statementofresponsibility by Thomas A. Pasquini. en_US
dc.format.extent 147 p. en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri en_US
dc.subject Physics. en_US
dc.title Quantum reflection of Bose-Einstein Condensates en_US
dc.title.alternative Quantum reflection of BECs en_US
dc.type Thesis en_US Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Physics. en_US
dc.identifier.oclc 317980304 en_US

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