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Master's Dissertation
DOI
10.11606/D.76.2010.tde-23042010-100355
Document
Author
Full name
Mônica Andrioli Caracanhas
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2010
Supervisor
Committee
Bagnato, Vanderlei Salvador (President)
Nussenzveig, Paulo Alberto
Oliveira, Marcos Cesar de
Title in Portuguese
Interações em condensados de Bose-Einstein: temperatura finita e gás dipolar
Keywords in Portuguese
Condensado
Interações dipolares
Temperatura finita
Abstract in Portuguese
Neste trabalho investigamos os efeitos das interações na expansão de um condensado de átomos de Rb. Dois problemas são abordados: o efeito de temperatura finita e as alterações introduzidas pela interação dipolar. No primeiro caso, dados experimentais não puderam ser explicados por meio da aproximação de Thomas-Fermi (TF) no regime de T = 0. Num condensado de cerca de 1 - 2 x 105 átomos condensados, o desvio da aproximação de TF ocorreu pelo fato de termos desconsiderado a interação dos átomos térmicos com os do condensado. Elaboramos um modelo teórico, baseado em modelos existentes de temperatura finita, o qual explicou relativamente bem os nossos resultados experimentais. No segundo problema atacado, foi analisada a variação na expansão do gás condensado quando a interação dipolar é incluída no sistema. Ambos os problemas mostram aspectos importantes da expansão de gases quânticos.
Title in English
Interactions in Bose-Einstein condensates: finite temperature and dipolar gas
Keywords in English
Condensate
Dipolar interactions
Finite temperature
Abstract in English
In this study we investigated the effects of interactions on the expansion of a condensate of Rb atoms. Two problems are addressed: the effect of finite temperature and the changes introduced by the dipolar interaction. In the first case, experimental data could not be explained by the Thomas-Fermi (TF) approach in the T = 0 regime. In a condensate of about 1 - 2 x 105 condensed atoms, the deviation of TF approach was due to the fact that we disregarded the interaction of thermal atoms those of the condensate. We developed a theoretical model, based on existing models of finite temperature, which explained relatively well our experimental results. In the second problem considered, we analyzed the variation in the expansion of the condensate gas when the dipolar interaction is included in the system. Both problems show important aspects of the expansion of quantum gases.
 
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Publishing Date
2010-05-04
 
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