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The late time behavior of disordered, wave bearing systems, acoustic, elastic or optical, has been of great interest in recent years. From a practical perspective, late time measurements correspond to large distances in a disordered system, and are thus relevant in many imaging or non-destructive evaluation applications. From a basic science perspective, late time observations can reveal interference behavior resulting from the approach to the Anderson transition, and offer the prospect of observing classical wave systems in a localized phase. While the Anderson transition has been theoretically predicted to occur in such systems for some time, clear evidence of a localized phase has unexpectedly been quite difficult to find. Our theoretical understanding of the current status is still incomplete, with continuing efforts employing direct numerical simulations, self-consistent, multiple scattering models, and field theoretic methods. Of these, direct numerical simulations and field theoretic methods enable a description of the localized phase. Direct numerical simulations, particularly those based on a monopole or dipole scattering approximation, have achieved some promising results but still describe highly idealized systems, and require substantial computational resources to describe systems substantially larger than a mean free path. Field theoretic methods on the other hand, while yielding semi-analytic results, have in the past been restricted to even more idealized systems. We discuss recent results in these areas, particularly with a view of moving towards a more realistic description of disordered, elastic systems. This research was funded by the Office of Naval Research.

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Douglas M. Photiadis, Naval Research Laboratory, Washington (D.C.)
Seminarraum Theoretische Physik
Contact: not specified