Physics – Condensed Matter – Disordered Systems and Neural Networks
Scientific paper
2011-01-11
J. Stat. Mech. (2011) P02031
Physics
Condensed Matter
Disordered Systems and Neural Networks
20 pages, 12 figures, 1 table. Note added on the recent work by Lepri et al
Scientific paper
10.1088/1742-5468/2011/02/P02031
We investigate the dynamics of a quantum particle in disordered tight-binding models in one and two dimensions which are exceptions to the common wisdom on Anderson localization, in the sense that the localization length diverges at some special energies. We provide a consistent picture for two well-known one-dimensional examples: the chain with off-diagonal disorder and the random-dimer model. In both cases the quantum motion exhibits a peculiar kind of anomalous diffusion which can be referred to as bi-fractality. The disorder-averaged density profile of the particle becomes critical in the long-time regime. The $q$-th moment of the position of the particle diverges with time whenever $q$ exceeds some $q_0$. We obtain $q_0=2$ for off-diagonal disorder on the chain (and conjecturally on two-dimensional bipartite lattices as well). For the random-dimer model, our result $q_0=1/2$ corroborates known rigorous results.
Krapivsky Paul. L.
Luck Mck. J.
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