Dresden 2003 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 44: Synchronisation II
DY 44.2: Hauptvortrag
Donnerstag, 27. März 2003, 15:00–15:30, G\"OR/226
Frequency and phase synchronization in stochastic systems — •Jan A. Freund1, Lutz Schimansky-Geier1, Robert Rozenfeld1, Alexander Neiman2, Stefan Linz3, Lars Callenbach4, and Peter Hänggi4 — 1Institut für Physik, Humboldt-Universität zu Berlin — 2Center for Neurodynamics, University of Missouri at St. Louis — 3Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster — 4Institut für Physik, Universität Augsburg
In parallel to the big boom of chaos synchronization, frequency and phase synchronization in stochastic systems have repeatedly received considerable interest. The revival of effective phase synchronization explains from the discovery that the phenomenon of stochastic resonance (SR), for large albeit subthreshold signals, can be reinterpreted in terms of a noise-induced phase synchronization (NIPS). In the presence of unbounded fluctuations, as they occur, for instance, in Gaussian noise, the concepts of frequency and phase synchronization need a revision yielding appropriate quantifiers of effective synchronization. After a short discussion of various phase concepts we will dwell on frequency synchronization in underdamped stochastic dynamics that is adequately described by the concept of the Rice frequency. In the overdamped limit the standard two-state description of a bistable potential is furnished with transition rates that explicitly depend on the phase difference. Analytic expressions for the average frequency and effective diffusion coefficient of the phase difference clearly reveal the conditions under which NIPS can occur. Applications to a signal detection problem (behavioral SR) and to a laser experiment (VCSEL) are briefly mentioned.