ISBN 978-3-8439-5032-9

978-3-8439-5032-9, Reihe Physik

Wolfgang Christoph Georges
The dynamical driven atom-cavity system: A realization beyond the open Dicke model

169 Seiten, Dissertation Universität Hamburg (2021), Softcover, A4

Zusammenfassung / Abstract

In this thesis, I report on three experiments with a dynamically driven atom-cavity system. The core of the experimental apparatus is a Bose-Einstein condensate of Rubidium atoms, which dispersively couples to the fundamental mode of a narrow linewidth optical cavity.

The advantage of the narrow linewidth is a retardation of the cavity light field dynamics, which leads to similar time scales of its evolution and the associated atomic motion.

The resulting atom-cavity interaction can be experimentally controlled by tuning the strength and frequency of an external pump field. A transversely pump with a strength above a critical threshold evokes a phase transition from a homogeneous superfluid phase to a spatially structured self-organized phase. Within some limitations, this is an experimental realization of the open Dicke model and builds the basis of the experiments presented here.

In the first part of this thesis, the infinite-range interaction for pump strengths below the critical threshold is studied. Therefore, a Bragg-spectroscopy-variant was used, which probes the excitation energy of the momentum states that corresponds to the self-organized phase by a short light pulse.

The second experimental part of this thesis focused on the suppression of the self-organized phase for pump strengths above the critical threshold. To dynamically change the atom-cavity coupling strength, the externally pumped atom-cavity system was extended by time-periodic amplitude modulation of the pump.

Finally, the understanding of the driven system was used to induce a transition between two density gratings of the dynamical density-wave order.