Optimal quantum control of Bose-Einstein condensates

This project is concerned with optimal quantum control of ultarcold atoms and Bose-Einstein condensates in atom chips. Optimal quantum control is a variant of optimal control theory, which allows to optimize a control objective subject to the condition that the system`s wavefunction evolves according to a Schrödinger-like equation. In typical atom chip experiments, the control is provided by the time-varying magnetic confinement fields and the objective is to channel the wavefunction between an initial and a desired state. Optimal quantum control can be used in the context of atom interferometry and nonlinear atom optics, as well as for optimizing quantum gates, and has been recently successfully employed for the design of control protocols that can be directly used experiment. The main goal of this project will be to investigate control in presence of correlations and thermal effects, and to devise control strategies that can be directly employed in state-of-the-art atom chip experiments.

This project has been concerned with optimal quantum control of ultracold atoms and Bose-Einstein condensates in atom chips. Optimal quantum control is a variant of optimal control theory, which allows optimizing a control objective subject to the condition that the system's wavefunction evolves according to a Schrödinger-like equation. In this project we have developed and published a simulation software suited for the simulation and optimization of various problems. We have used this software to study the preparation of non-classical states, as required for twin-atom production and atom interferometry, and have compared different optimization approaches. In addition, we have developed theoretical description schemes based on the density matrix formalism which can be used for an efficient simulation of thermal excitations and condensate fragmentation; these investigation turned out to be more complicated than initially thought, and we could not find a fully satisfactory solution within this project.