Berlin 2012 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 10: Nonlinear Dynamics, Synchronisation and Chaos

DY 10.3: Vortrag

Dienstag, 27. März 2012, 10:00–10:15, MA 001

Intraband dynamics in a one dimensional (1D) nonlinear Wannier-Stark ladder — •Petruta Anghel-Vasilescu and Sergej Flach — Max-Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany

I will present new results on the dynamics of a wave packet in a 1D nonlinear Wannier-Stark ladder in the absence of interband Landau-Zener tunneling and discuss the observed different regimes of spreading of an initial single-site excitation. In the linear Wannier- Stark problem, the eigenvalue spectrum is equidistant and all normal modes are spatially localized. Nonlinearity induces frequency shifts and mode-to-mode interactions which can destroy the localization. For large values of the nonlinear coefficient we observe single-site trapping as a transient regime, followed by an explosive spreading and subdiffusion. For moderate nonlinearity strength the subdiffusion is found to be the only spreading regime. Finally for small nonlinearities we find linear Stark localization due to the presence of nonlinear Bloch oscillations. The sub-diffusive spreading was found to be very dependent on the strength of the applied electric field.