Optimal Control of Bose-Einstein Condensates

Ulrich Hohenester

Published Jan 1, 2012• 0 citations

Abstract

In this thesis we use optimal control theory to control a BoseEinstein condensate. We focus on an experiment conducted at the Vienna University of Technology where a Bose-Einstein condensate is produced and trapped on an atom chip, and two entangled matter waves are produced. Such a twin atom beam has many technical applications and is necessary for matter wave interferometry, for example. One critical step in this experiment is the excitation of the condensate, which is achieved by displacing the minimum of the confinement potential (“shaking”). In order to find a time dependent potential that excites the condensate, optimal control theory is necessary and able to produce satisfying results. However, theoretical predictions and experimental data do not match perfectly. This is mainly due to the impulse response filter, causing a difference between the calculated and the experimentally accessible control field. To solve this problem in this thesis, we incorporate the effect of this impulse response filter in the optimal control algorithm. The new system is then not local in time anymore and there are new boundary conditions to meet. These problems are overcome and the obtained control fields are much closer to the experiment than without considering the effects of the impulse response filter. It is even possible to find working control fields with a transition time of only two milliseconds or to transfer the condensate in a higher excited state.

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