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Realization of Bose-Einstein Condensation of 87Rb in a Time-orbiting Potential Trap

The construction of an apparatus capable of producing Bose-Einstein condensates marks a significant milestone in every experimental cold atom laboratory. In this thesis I describe the development of a system to create a Bose-Einstein condensate of $^{87}Rb$ in a Time-Orbiting Potential trap.

I review the optical and magnetic techniques required to trap and cool an atomic sample under vacuum, motivating our decision to build a double MOT system comprised of a high-pressure ($10^{-9}$ torr) chamber to gather atoms and a low-pressure ($10^{-11}$ torr) chamber to cool atoms to degeneracy.

By theoretically modeling the atom number and temperature inside the magnetic trap during evaporative cooling I demonstrate a simple approach to determining a cooling path that reaches the transition temperature. By making use of the condensates produced under these non-optimized conditions I determine the heating rate of the condensate in the TOP trap to be $300$ nK/s. I further use the condensates to make a more precise measurement of the TOP trap bias field.

I improve upon the conventional evaporation path used in TOP trap experiments by introducing and optimizing additional bias field compression stages in between RF evaporation ramps. I demonstrate how, by adding these additional stages, the system is capable of reaching the BEC phase transition with a final atom number of $2\times 10^{5}$. In contrast, RF evaporation after only a single bias field ramp has yielded condensates with only $30\times 10^3$ atoms.

Identiferoai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/27604
Date13 June 2011
CreatorsSiercke, Mirco
ContributorsSteinberg, Aephraim
Source SetsUniversity of Toronto
Languageen_ca
Detected LanguageEnglish
TypeThesis

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