TY  - GEN
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/25592/
Y1  - 2018///
A1  - Beinke, Raphael
TI  - Excitations and dynamics of Bose-Einstein condensates: A many-body approach
ID  - heidok25592
AV  - public
N2  - This thesis explores the dynamics and especially the low-energy spectra of Bose-Einstein condensates (BECs) in one- and two-dimensional potential traps. Of particular interest are many-body effects. To obtain numerically exact results for the dynamics, the well-established multiconfigurational time-dependent Hartree for bosons (MCTDHB) method is applied. Excited states are calculated utilizing the recently introduced linear-response theory atop it (LR-
MCTDHB). The core of the latter theory is an in general non-hermitian eigenvalue problem. The newly developed implementation of this theory is described in detail and benchmarked towards the exactly-solvable harmonic-interaction model. Several applications are discussed.
With respect to dynamics, it is shown that both the out-of-equilibrium tunneling dynamics and the dynamics of trapped vortices are of many-body nature. Furthermore, many-body
effects in the excitation spectra are presented for BECs in different trap geometries. It is demonstrated that even for essentially-condensed systems, the spectrum of the lowest-in-energy excitations computed at the many-body level differs substantially from a standard mean-field description. In general, it is shown that bosons carrying angular momentum are more sensitive to many-body effects, both in the dynamics and the excitation spectrum.
ER  -