Anomalous transport regime in a non-Hermitian Anderson-localized hybrid system

Abstract

In a disordered environment, the average transmission of a propagating wave falls with increasing disorder. Beyond a crossover, transport is arrested because the wave is trapped in the bulk of the sample with exponentially decaying coupling to the boundaries due to Anderson localization. Here, we report the experimental demonstration of anomalous transport of hybrid particles under localizing disorder in a non-Hermitian setting. We create hybrid polariton-photon states in a one-dimensional copper sample with a comb-shaped periodic microstructure designed for microwave frequencies. Non-Hermiticity arises from multiple loss channels existing in the real experimental sample. Disorder is introduced by deliberate alterations of the periodic microstructure. Direct measurement of wave functions was achieved by a near-field probe. At a particular disorder, we observe the onset of Anderson localization of the hybrid states attested to by the exponential tails of the wave function. However, at stronger disorder and under conditions that support localization, an unexpected enhancement in the transmission was facilitated by an emergent miniband. The transmission was traced to the hopping of the hybrid particle over multiple coexisting localized resonances that exchange energy due to the nonorthogonality. These emergent states are manifested in all configurations under strong disorder, suggesting a novel transport regime. This is verified by measuring the averaged conductance which indicates an anomalous transport regime in the hybrid, non-Hermitian environment under strong disorder. These experimental observations open up new unexplored avenues in the ambit of disorder under non-Hermitian conditions.