Structure and Collapse of a Dipolar Bose-Einstein Condensate

Boaz Ilan, Jessica Taylor

Ryan Wilson, Shai Ronen, John L. Bohn

We explore the structure and dynamics of dipolar Bose-Einstein condensates (DBECs) near their threshold for instability. Near this threshold a DBEC may exhibit nontrivial biconcave density distributions, which are associated with instability against collapse into ``angular roton'' modes. Here we discuss experimental signatures of these features. In the first, we infer local collapse of the DBEC from the experimental stability diagram. In the second, we explore the dynamics of collapse and find that a nontrivial angular distribution is a signature of the DBEC possessing a biconcave structure.

Yuki Kawaguchi, Hiroki Saito, Masahito Ueda

Carlo F. Barenghi, Thomas Bland, Nick G. Parker

Stefan Müller

The subject of this thesis is the experimental investigation of a dipolar 52-Chromium Bose-Einstein condensate (BEC) in a one-dimensional optical lattice potential. At first, the influence of the periodic landscape on the stability of the quantum gas is investigated. Based on these measurements, the collapse dynamics of the system, i.e. its time evolution after passing the threshold to the unstable regime, is observed and analyzed. Both the investigations aim to contribute to the basic understanding of dipolar quantum gases. In addition, they may provide a basis for further experiments with dipolar BECs in optical lattices. Amongst others, the observation of self-organized density structures is one of the biggest goals in this field of research.

Jing-Min Hou, Tiantao Zhao, Lijie Zhang