Localization in coupled heterogeneously disordered transport channels on the Bethe lattice

TL;DR

This paper investigates how coupling dissimilar transport channels affects localization in systems like exciton-polaritons, revealing that higher-dimensional Bethe lattices tend to preserve delocalization despite strong disorder in one channel.

Contribution

It extends the understanding of Anderson localization in coupled heterogeneously disordered channels from 1D to Bethe lattices, highlighting the role of dimensionality.

Findings

In 1D, the dirtier channel dominates localization.

On the Bethe lattice, delocalized channels remain delocalized when coupled.

Dimensionality critically influences localization behavior.

Abstract

We study the Anderson localization in systems, in which transport channels with rather different properties are coupled together. This problem arises naturally in systems of hybrid particles, such as exciton-polaritons, where it is not obvious which transport channel dominates the coupled system. Here we address the question of whether the coupling between a strongly and a weakly disordered channel will result in localized (insulating) or delocalized (metallic) behavior. Complementing an earlier study in 1D [H. Y. Xie, V. E. Kravtsov, and M. M\"uller, Phys. Rev. B \textbf{86} 014205 (2012)], the problem is solved here on a bilayer Bethe lattice with parametrically different parameters. The comparison with the analytical solution in 1D shows that dimensionality plays a crucial role. In D=1 localization is in general dominated by the dirtier channel, which sets the backscattering rate. In contrast, on the Bethe lattice a delocalized channel remains almost always delocalized, even when coupled to strongly localized channels. We conjecture that this phenomenology holds true for finite dimensions $D>2$ as well. Possible implications for interacting many-body systems are discussed.