Dresden 2006 – scientific programme

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.32: Poster

Thursday, March 30, 2006, 16:00–18:00, P1

Control of noise-induced patterns in a semiconductor nanostructure — •Grischa Stegemann¹, Alexander Balanov^1,2, and Eckehard Schöll¹ — ¹Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin — ²School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD

We study the constructive influence of noise upon the nonlinear dynamics of current density patterns in a semiconductor nanostructure, and its control by time delayed feedback methods. In particular, we investigate noise-induced pattern formation in a double barrier resonant tunnelling diode described by a nonlinear reaction-diffusion model.

The parameters of the system are fixed at values below a Hopf bifurcation where the only stable state of the deterministic system is a spatially inhomogeneous "filamentary" steady state, and oscillating space-time patterns do not occur. We show that the addition of weak Gaussian white noise to the system gives rise to spatially inhomogeneous oscillations. As the noise intensity grows, the oscillations tend to become more and more spatially homogeneous, while simultaneously the temporal coherence of the oscillations decreases. We demonstrate that the application of a time delayed feedback loop, similar to that used in deterministic chaos control, allows one to either increase or decrease the regularity of the noise induced dynamics in this spatially extended system. Using linear stability analysis we can explain these effects, depending on the length of the delay interval.