Cavity-assisted mesoscopic transport of fermions: Coherent and dissipative dynamics

TL;DR

This paper investigates how light-matter interactions in a mesoscopic fermionic chain influence charge transport, revealing regimes where cavity decay and coupling enhance steady-state currents and induce delocalized states.

Contribution

It introduces and benchmarks methods for analyzing open quantum systems, and uncovers how cavity parameters control transport and state localization in fermionic chains.

Findings

Steady-state current enhancement scales with cooperativity in dissipative regimes.

Resonant Bloch states transfer properties between bands in high-finesse cavities.

Current enhancement arises from collective decay in low-quality cavities.

Abstract

We study the interplay between charge transport and light-matter interactions in a confined geometry, by considering an open, mesoscopic chain of two-orbital systems resonantly coupled to a single bosonic mode close to its vacuum state. We introduce and benchmark different methods based on self-consistent solutions of non-equilibrium Green's functions and numerical simulations of the quantum master equation, and derive both analytical and numerical results. It is shown that in the dissipative regime where the cavity photon decay rate is the largest parameter, the light-matter coupling is responsible for a steady-state current enhancement scaling with the cooperativity parameter. We further identify different regimes of interest depending on the ratio between the cavity decay rate and the electronic bandwidth. Considering the situation where the lower band has a vanishing bandwidth, we show that for a high-finesse cavity, the properties of the resonant Bloch state in the upper band are transfered to the lower one, giving rise to a delocalized state along the chain. Conversely, in the dissipative regime with low cavity quality factors, we find that the current enhancement is due to a collective decay of populations from the upper to the lower band.