ISBN 978-3-8439-2677-5

978-3-8439-2677-5, Reihe Physik

Holger Kadau
Rosensweig Instability and Droplets in a Quantum Ferrofluid of Dysprosium Atoms

140 Seiten, Dissertation Universität Stuttgart (2016), Softcover, A5

Zusammenfassung / Abstract

Quantum gases can act as model systems for condensed matter phenomena, especially dipolar quantum gases can exhibit spontaneous symmetry breaking owing to the long-range and anisotropic character of the interactions. In particular, a Bose-Einstein condensate with dipolar interaction can act as a quantum ferrofluid which, in analogy to a classical ferrofluid, has been predicted to exhibit a Rosensweig instability where the translational symmetry is broken and self-organized structures form. In this thesis, we experimentally observe this effect in a dipolar Bose-Einstein condensate of dysprosium atoms. This manifests itself in a transition from a superfluid to a state with ordered droplet ensembles. Prior to this work, the resulting quantum droplets were expected to collapse at the mean-field level due to an essentially attractive interaction. However, we observe them to be stable and demonstrate quantitatively that quantum fluctuations, a consequence of Heisenberg's uncertainty principle, stabilize the droplets against the expected collapse.