Author: Mirco SierckePublisher:
ISBN: 9780494777251
Category :
Languages : en
Pages : 244
Book Description
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 87RB 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 2x 105. In contrast, RF evaporation after only a single bias field ramp has yielded condensates with only 30 x 103 atoms.
