Destruction of Anderson localization by subquadratic nonlinearity
| Autor: | Alexander Milovanov, Alexander Iomin |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Europhysics Letters. 141:61002 |
| ISSN: | 1286-4854 0295-5075 |
| DOI: | 10.1209/0295-5075/acc19c |
| Popis: | It is shown based on a mapping procedure onto a Cayley tree that a subquadratic nonlinearity destroys Anderson localization of waves in nonlinear Schrödinger lattices with randomness, if the exponent of the nonlinearity satisfies , giving rise to unlimited subdiffusive spreading of an initially localized wave packet along the lattice. The focus on subquadratic nonlinearity is intended to amend and generalize the special case s = 1, considered previously, by offering a more comprehensive picture of dynamics. A transport model characterizing the spreading process is obtained in terms of a bifractional diffusion equation involving both long-time trappings of unstable modes on finite clusters and their long-haul jumps in wave number space consistent with Lévy flights. The origin of the flights is associated with self-intersections of the higher-order Cayley trees with odd coordination numbers z > 3 leading to degenerate states. |
| Databáze: | OpenAIRE |
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