Regensburg 2010 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 29: Spatially Extended Dynamical Systems
DY 29.6: Talk
Thursday, March 25, 2010, 15:15–15:30, H46
Delocalization and spreading in a nonlinear Stark ladder — •Dmitry Krimer1, Sergej Flach1, and Ramaz Khomeriki1,2 — 1Max Planck Institute for the Physics of Complex Systems, Dresden — 2Physics Department, Tbilisi State University, Chavchavadze 3, 0128 Tbilisi, Georgia
We study the evolution of a wave packet in a nonlinear Stark ladder [1]. In the absence of nonlinearity all normal modes are spatially localized giving rise to an equidistant eigenvalue spectrum and Bloch oscillations. Nonlinearity induces frequency shifts and mode-mode interactions. For large strength of nonlinearity we observe a long lived trapped regime with an explosive transition to Bloch oscillations, followed by a subdiffusive spreading at large time scales. For moderate nonlinearities an immediate subdiffusion takes place. Finally, for small nonlinearities we find linear Stark localization as a transient, with subsequent subdiffusion. For single mode excitations and weak nonlinearities stability intervals are predicted and observed upon variation of the dc bias strength, which affect the short and long time dynamics. In all cases, we observe that nonlinearity destroys integrability, introduces chaos, and ultimately leads to a destruction of localization.
[1] D.O. Krimer, R. Khomeriki and S. Flach, Phys. Rev. E 80, 036201 (2009)