One-dimensional electron localization in semiconductors coupled to electromagnetic cavities

TL;DR

This paper investigates how embedding 1D disordered semiconductors in electromagnetic cavities modifies their electron localization and conductivity, revealing Fano resonances and conductance enhancements due to cavity coupling.

Contribution

It introduces a non-perturbative Green's function approach to analyze cavity-induced effects on electron localization and transport in disordered 1D systems.

Findings

Fano-type resonances appear in the electron transmission spectrum due to cavity effects.

Coupling to the cavity enhances low-temperature conductance by raising shallow bound state energies.

Resonance quality depends on the localization of intermediate states within the disorder potential.

Abstract

Electrical conductivity of one-dimensional (1d) disordered solids decays exponentially with their length, which is a celebrated manifestation of the localization phenomenon. Here, we study the modifications of localized conductivity induced by placement of 1d semiconductors inside of single-mode electromagnetic cavities, focusing on the regime of non-degenerate doping. We use the Green's function technique modified for the non-perturbative account of cavity excited states, and including both coherent electron-cavity effects (i.e. electron motion in the zero-point fluctuating field) and incoherent processes of photon emission upon tunneling. The energy spectrum of electron transmission in the cavity acquires Fano-type resonances associated with virtual photon emission, passage along the resonant level, and photon re-absorption. The quality factor of the Fano resonance depends on whether the intermediate state is coupled to the leads, and reaches its maximum when this state is localized deep in the disorder potential. Coupling to the cavity also elevates the energies of the shallow bound states, bringing them to the conduction band bottom. Such an effect leads to the enhancement of the low-temperature conductance.