Regensburg 2016 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 26: Poster - Quanten Systems
DY 26.11: Poster
Dienstag, 8. März 2016, 18:15–21:00, Poster C
Self-localization of Bose-Einstein condensates in leaking optical lattices — •Johannes Kruse and Ragnar Fleischmann — Max Planck Institute for Dynamics and Self-Organization, 37073 Göttingen, Germany
Mean field and beyond mean field model calculations of Bose-Einstein condensates trapped in optical lattices have shown that initially homogeneous condensates can evolve into self-trapped, strongly localized states in the presence of weak boundary dissipation, a phenomenon called self-localization. A phase transition from extended to localized states has been observed when the effective nonlinearity exceeds a critical threshold Λeffb.
We investigate the phase transition to self-localization in the mean field approximation of the discrete nonlinear Schrödinger equation. Earlier, based on the concept of the Peierls-Nabarro barrier an analytical upper bound for Λeffb as a function of the system size had been found. We now propose and numerically verify an analytical lower bound for Λeffb, linking it to the phenomenon of Anderson localization. Moreover we quantitatively characterize the properties of the nonlinear localized solutions, so called discrete breathers, directly after the phase transition. The results strongly suggest that in the thermodynamic limit the average shape of the solutions at the transition approaches a fixed limiting profile located in the center of the lattice.