Cover showing time-of-flight images of a F=1 Bose Einstein condensate, center-of-mass motion of an ultracold gas in a TOP trap and a spinning TOP. Design and implementation by dr Antje Ludewig. number of hard copies of this thesis is available there. A digital version of this thesis can be downloaded from www.science.uva.nl/ walraven This work is part of the research programme of the Foundation...

The problem of particle fluctuations in arbitrary nonuniform systems with BoseEinstein condensate is considered. This includes the case of trapped Bose atoms. It is shown that the correct description of particle fluctuations for any nonuniform system of interacting atoms always results in thermodynamically normal fluctuations.

In this paper we show that for a non-ideal Bose gas there exists an upper limit on the transition temperature above which Bose-Einstein condensation cannot occur regardless of the pressure applied. Such upper limits for some realistic Bose gases are estimated. This result implies that there may also exist an upper limit on the transition temperature of super-

This paper deals with mathematical questions for Bose gases below the temperature TBEC where Bose-Einstein condensation sets in. The model considered is of two-component type, consisting of a kinetic equation for the distribution function of a gas of (quasi-)particles interacting with a Bose condensate, which is described by a Gross-Pitaevskii equation. Existence results and moment estimates ar...