Hannover 2013 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 45: Quantum gases: Bosons II

Q 45.2: Vortrag

Donnerstag, 21. März 2013, 11:15–11:30, F 342

Roton confinement in a trapped dipolar Bose-Einstein condensate — Mattia Jona Lasinio, •Kazimierz Łakomy, and Luis Santos — Institut für Theoretische Physik, Leibniz Universität, Hannover, Appelstrasse 2, D-30167 Hannover, Germany

Roton-like excitations constitute the key feature of dipolar gases, linking these systems to superfluid Helium. We show that the inherent locality of the roton spectrum in a trapped dipolar condensate results in the spatial confinement of rotons. As a result, roton instability leads to the appearance of localized density patterns which, depending on parameters of the system and fluctuations, can acquire the form of concentric rings. The localized modulational instability gives rise to a peculiar post-collapse dynamics which lacks the typical d-wave symmetry, characteristic for the global collapses in a dipolar condensate. Moreover, induced roton instability may be employed to create a gas of trapped roton excitations, with characteristic persistent density modulations confined in the center of the trap. Other consequences of the local roton spectrum are also discussed, including local susceptibility against a perturbation of the condensate, which leads to an inhomogeneous vortex lattice.