Dresden 2009 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 3: Nonlinear dynamics, synchronization and chaos I
DY 3.6: Vortrag
Montag, 23. März 2009, 12:15–12:30, ZEU 118
Spreading of wavepackets in one dimensional disordered chains- II. Spreading mechanisms — •Dmitry Krimer, Sergej Flach, and Charalampos Skokos — Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, D-01187 Dresden, Germany
As is discussed in the first part of this presentation, there are three different types of the evolution of a wavepacket in discrete disordered nonlinear Schrödinger and anharmonic oscillator chains: I) localization as a transient, with subsequent subdiffusion; II) the absence of the transient and immediate subdiffusion; III) selftrapping of a part of the packet, and subdiffusion of the remainder. Here we focus on the mechanisms that explain subdiffusive spreading of the wavepacket which is due to weak but nonzero chaotic dynamics inside the packet. Chaos is a combined result of resonances and nonintegrability. As a result the mode outside the packet is heated by the packet nonresonatly. We estimate the number of resonant modes in the packet and study the nature of resonant mode pairs by performing a statistical numerical analysis. The predicted second moment of the packet is increasing as t1/3 which is in a good agreement with our numerical findings.