Hizanidis Johanne, Schöll Eckehard
Instutut für Theoretische Physik, Technische Universität Berlin, Hardenbergstasse 36, D-10623 Berlin, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Dec;78(6 Pt 2):066205. doi: 10.1103/PhysRevE.78.066205. Epub 2008 Dec 5.
We study the effect of time-delayed feedback control and Gaussian white noise on the spatiotemporal charge dynamics in a semiconductor superlattice. The system is prepared in a regime where the deterministic dynamics is close to a global bifurcation, namely, a saddle-node bifurcation on a limit cycle. In the absence of control, noise can induce electron charge front motion through the entire device, and coherence resonance is observed. We show that with appropriate selection of the time-delayed feedback parameters the effect of coherence resonance can be either enhanced or destroyed, and the coherence of stochastic domain motion at low noise intensity is dramatically increased. Additionally, the purely delay-induced dynamics in the system is investigated, and a homoclinic bifurcation of a limit cycle is found.
我们研究了延迟反馈控制和高斯白噪声对半导体超晶格中时空电荷动力学的影响。该系统处于确定性动力学接近全局分岔的状态，即极限环上的鞍结分岔。在没有控制的情况下，噪声可诱导电子电荷前沿穿过整个器件运动，并观察到相干共振。我们表明，通过适当选择延迟反馈参数，相干共振的效果可以增强或破坏，并且在低噪声强度下随机畴运动的相干性会显著增加。此外，还研究了系统中纯粹由延迟引起的动力学，并发现了极限环的同宿分岔。
