Berlin 2018 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
DY: Fachverband Dynamik und Statistische Physik
DY 60: Anomalous Diffusion (joint session DY/BP)
DY 60.4: Vortrag
Donnerstag, 15. März 2018, 10:45–11:00, BH-N 334
Sinai type diffusion in Gaussian random potentials with decaying spatial correlations — •Igor Goychuk1, Vasyl O. Kharchenko2, and Ralf Metzler1 — 1Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany — 2Institute of Applied Physics, Natl. Acad. Sci. Ukraine, Sumy, Ukraine
Logarithmic subdiffusion is usually associated with random force disorder and non-stationary potential fluctuations whose root mean squared amplitude grows with distance. We show that such Sinai type diffusion also universally emerges at sufficiently low temperatures in stationary Gaussian random potentials with spatially decaying correlations, known to exist in a broad range of physical systems. Combining results from extensive simulations with a scaling
approach we elucidate the physical mechanism of this unusual subdiffusion. In particular, we explain why with growing temperature and/or time a first crossover occurs to standard, power-law subdiffusion and then a second crossover occurs to normal diffusion with a disorder-renormalized diffusion coefficient. Interestingly, the initial, nominally ultraslow diffusion turns out to be much faster than the universal de Gennes-Bässler-Zwanzig limit of the renormalized normal diffusion, which realistically cannot be attained at sufficiently low temperatures and/or for strong disorder. The ultraslow diffusion is also shown to be non-ergodic and it displays a local bias phenomenon. Our simple scaling theory not only explains our numerical findings, but also has a predictive character.
Funded by the DFG, Grant GO 2052/3-1