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Observation of the Castaing instability in a trapped ultracold Bose gas

Resource type
Thesis type
(Thesis) M.Sc.
Date created
2013-04-15
Authors/Contributors
Abstract
Ultracold trapped atomic systems are ideal model systems to investigate physical phenomena in the quantum regime. In this work we studied instabilities in spin dynamics of a sample of nondegenerate trapped $^{87}$Rb gas. This is the first experimental investigation of the so-called Castaing instability in such systems. The Castaing instability is an instability in the spin dynamics of spin-polarized systems as a result of introducing sharp spin gradients in their spin profile. We used an optical technique via the ac Stark effect to initialize arbitrary spin profiles in a sample of evaporatively cooled nondegenerate $^{87}$Rb gas. The experimental results manifest evidence for the presence of the Castaing instability in both transverse and longitudinal spin channels. The results agree reasonably well with theoretical studies and results of a numerical solution to the spin transport equation. Some imperfection in the longitudinal spin gradient due to the spin-state preparation technique makes the signature of the instability less clear in the transverse channel. We propose another preparation technique to overcome this shortcoming in future experiments.
Document
Identifier
etd7817
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The author granted permission for the file to be printed, but not for the text to be copied and pasted.
Scholarly level
Supervisor or Senior Supervisor
Thesis advisor: McGuirk, Jeffrey M.
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etd7817_DNiroomand.pdf 3.84 MB

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