Absence of Anderson localization in certain random lattices

TL;DR

This paper experimentally investigates how specific long-range correlations in a 1D disordered system can suppress Anderson localization, leading to a transition from localized to conductive behavior, highlighting the importance of correlation type.

Contribution

It demonstrates that power-law spectral correlations with an exponent greater than 2 can prevent Anderson localization in 1D systems, contrasting with other correlation types that enhance localization.

Findings

Long-range correlations with spectral density power > 2 suppress localization.

Transmission peaks merge into a pass band under certain correlations.

Different long-range correlations can have opposite effects on localization.

Abstract

We report on the transition between an Anderson localized regime and a conductive regime in a 1D scattering system with correlated disorder. We show experimentally that when long-range correlations, in the form of a power-law spectral density with power larger than 2, are introduced the localization length becomes much bigger than the sample size and the transmission peaks typical of an Anderson localized system merge into a pass band. As other forms of long-range correlations are known to have the opposite effect, i.e. to enhance localization, our results show that care is needed when discussing the effects of correlations, as different kinds of long-range correlations can give rise to very different behavior.