Evaporative Cooling of a Bose Gas and Interacting Spinor Condensates

Abstract

This thesis reports on the two projects I have completed during my Bachelor's research at the Bose Einstein Condensate (BEC) research group of Peter van der Straten: optimizing evaporative cooling and measuring interactions between spinor condensates.

To create a BEC, the process of evaporative cooling is used. This process is modeled and optimized using a Monte-Carlo optimization, which shows that the lab procedure can be improved to gain up to 13% particles at Tc in a speci fic situation. The optimization also shows that expanding the trap volume during the cooling process is less efficient than keeping the volume at the smallest achievable value in our setup, since the densities are not high enough for the loss processes to dominate.

To measure spin drag in BEC's, a measurement is prepared in the far off resonance trap in which two spinor condensates are accelerated towards a third condensate, where all three condensates are in diff erent spin states. The measurement shows that under the speci fic conditions of the experiment, the condensates collide inelastically. It was hypothesized that this could be explained by the immiscibility of di fferent spin condensates. This is refuted, since the force due to immiscibility is one order of magnitude smaller than necessary to explain the motion of the condensates.