Dynamics of Bose-Einstein condensation in lithium-7

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dc.contributor.advisor Hulet, Randall G.
dc.creator Sackett, Charles Ackley 2009-06-04T06:56:05Z 2009-06-04T06:56:05Z 1999
dc.description.abstract Bose-Einstein condensation (BEC) of 7Li has been investigated. Because the effective interaction between 7Li atoms is attractive, the condensate occupation number N 0 is limited to ∼ 1250 atoms, and when this limit is exceeded, the condensate becomes unstable with respect to mechanical collapse. The interplay of this limit and the natural growth of the condensate during BEC leads to complicated dynamical behavior, which has been studied both theoretically and experimentally. It has been modeled by solving the quantum Boltzmann equation, in conjunction with results from the nonlinear Schrodinger equation. It is found that N0 oscillates rapidly as the condensate alternately fills and collapses, and that the oscillations can persist for many cycles before the gas comes to equilibrium. Experimental evidence for these oscillations was obtained by repeatedly producing a condensate and measuring N 0. The results were seen to vary randomly from one measurement to the next, which is to be expected as the timing of the oscillations is intrinsically stochastic. The distribution of N0 values occurring was measured, and provides quantitative information on the condensate growth and collapse. The equilibration process itself was also observed, by quenching the gas into degeneracy and observing its relaxation. In order to carry out these experiments, sensitive measurement and analysis techniques were developed which enabled N0 to be determined in situ with an accuracy of +/-20% and a precision of +/-60 atoms. The theoretical tools used to study quantum degenerate gases were also applied to the important experimental technique of evaporative cooling, which led to substantial optimization and improvements. As part of this study, the rate constant for dipolar relaxation was measured to be 1.05 +/- 0.1 x 10-14 cm3/s, in agreement with theoretical predictions.
dc.format.extent 203 p.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subject Physics, Atomic
dc.title Dynamics of Bose-Einstein condensation in lithium-7
dc.type.genre Thesis
dc.type.material Text Physics Rice University Doctoral Doctor of Philosophy
dc.identifier.citation Sackett, Charles Ackley. (1999) "Dynamics of Bose-Einstein condensation in lithium-7." Doctoral Thesis, Rice University.

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