title: Spreading of wave packets in disordered systems with tunable nonlinearity.
abstract: We study the spreading of single-site excitations in one-dimensional disordered Klein-Gordon chains with tunable nonlinearity |u(l)|(σ)u(l) for different values of σ. We perform extensive numerical simulations where wave packets are evolved (a) without and (b) with dephasing in normal-mode space. Subdiffusive spreading is observed with the second moment of wave packets growing as t(α). The dependence of the numerically computed exponent α on σ is in very good agreement with our theoretical predictions both for the evolution of the wave packet with and without dephasing (for σ≥2 in the latter case). We discuss evidence of the existence of a regime of strong chaos and observe destruction of Anderson localization in the packet tails for small values of σ.
authors.affiliation: Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.
authors.forename: Ch
authors.initials: Ch
authors.lastname: Skokos
authors.forename: S
authors.initials: S
authors.lastname: Flach