Multi-mode Deep Strong Coupling in a Multi Quantum Well Fabry-Perot Cavity

TL;DR

This paper demonstrates multi-mode deep-strong light-matter coupling in a multi-quantum well Fabry-Perot cavity, revealing complex polaritonic spectra and light-matter decoupling phenomena with potential for advanced chiral photonic applications.

Contribution

It introduces a multi-mode deep-strong coupling system in a quantum well heterostructure with a comprehensive all-to-all coupling model and observes unprecedented decoupling effects.

Findings

Vacuum Rabi splitting exceeds mode spacing

Normalized coupling strength reaches η=8.1

Observation of light-matter decoupling across spectrum

Abstract

We present multi-mode deep-strong coupling in a multi-quantum well (N=166) heterostructure. The heterostructure itself acts as a Fabry-Perot cavity, for which the even cavity modes strongly couple to the cyclotron resonance to form Landau polaritons. The experimentally observed vacuum Rabi splitting is larger than the mode spacing and well into the deep-strong coupling regime ($\eta>1$) resulting in a rich multi-mode polaritonic spectrum which is accurately reproduced by an all-to-all multi-photonic, multi-electronic Hopfield coupling model. Remarkably, light-matter decoupling is observed across the whole measurable spectrum, including in the low frequency limit ($\lambda>>L_{cav}$) where the normalized coupling strength reaches $\eta=8.1$. The system demonstrates a robust platform for exploring extreme coupling regimes and its chiral nature holds potential for chiral cavity and chiral mirror applications.