Optimized evaporative cooling using a dimple potential: An efficient route to Bose-Einstein condensation
Journal of Physics B: Atomic, Molecular and Optical Physics 37:15 (2004) 3187-3195
Abstract:
The realization of Bose-Einstein condensation of 133Cs relies on an innovative evaporative cooling technique using a dimple potential. Correctly loading an atomic gas into such a potential produces a dense sample with a high phase space density, ideal for evaporative cooling. We have numerically simulated both the loading process and the subsequent evaporative cooling from a dimple potential in order to elucidate the optimization of this technique. Furthermore, we demonstrate that this technique would be effective in cooling 85Rb to quantum degeneracy and describe a simple scheme for its implementation.Dynamic optical trap generation using FLC SLMs for the manipulation of cold atoms
Journal of Modern Optics 51:14 (2004) 2235-2240
Abstract:
Trapping and manipulation of cold atoms using optical potentials require the ability to generate and control a time varying light intensity distribution. Such an application demands that fast changing intensity distributions are generated, which are however free from flickering, or noise in general. Ferroelectric spatial light modulators are good candidates to achieve this because of their high refresh rate but they suffer from noise due to changes in the state of individual pixels during an animated sequence. A direct binary search based optimization routine was developed which minimizes the noise during such sequences. Filter sequences designed using this technique have been tested experimentally and the results demonstrated that flicker noise was eliminated. © 2004 Taylor & Francis Group, LLC.Experimental observation of a superfluid gyroscope in a dilute Bose-Einstein condensate.
Phys Rev Lett 91:9 (2003) 090403
Abstract:
We have observed a three-dimensional gyroscopic effect associated with a vortex in a dilute Bose-Einstein condensed gas. A condensate with a vortex possesses a single quantum of circulation, and this causes the plane of oscillation of the scissors mode to precess around the vortex line. We have measured the precession rate of the scissors oscillation. From this we deduced the angular momentum associated with the vortex line and found a value close to Planck's over 2pi per particle, as predicted for a superfluid.The evaporative cooling of a gas of caesium atoms in the hydrodynamic regime
Journal of Physics B: Atomic, Molecular and Optical Physics 36:16 (2003) 3533-3540
Abstract:
We study the efficiency of evaporative cooling of a trapped gas of caesium atoms in the hydrodynamic regime by the numerical solution of classical kinetic theory equations. The results of the numerical simulation are compared to our experimental observations of evaporative cooling of magnetically trapped 133Cs atoms in the F = 3, MF = -3 state. The simulation accurately reproduces our experimental performance and indicates that the reduction in cooling efficiency as the gas enters the hydrodynamic regime is the main obstacle to the realization of Bose-Einstein condensation (BEC) in this state. The simulation is used to explore alternative routes to BEC.Strong evaporative cooling towards Bose-Einstein condensation of a magnetically trapped caesium gas
Journal of Optics B: Quantum and Semiclassical Optics 5:2 (2003)