Rydberg Exciton-Polaritons in a Magnetic Field

TL;DR

This paper presents a comprehensive microscopic theory of Rydberg exciton-polaritons in 2D semiconductor heterostructures under magnetic fields, accurately modeling their wave functions, energies, and interactions, and aligning well with experimental data.

Contribution

It introduces a novel microscopic approach that captures the effects of magnetic fields on Rydberg excitons and polaritons, surpassing previous perturbative methods.

Findings

Exciton wave functions shrink with increasing magnetic field.

Theoretical polariton energies match experimental measurements.

The model captures strong light-matter coupling effects beyond perturbation theory.

Abstract

We theoretically investigate exciton-polaritons in a two-dimensional (2D) semiconductor heterostructure, where a static magnetic field is applied perpendicular to the plane. To explore the interplay between magnetic field and a strong light-matter coupling, we employ a fully microscopic theory that explicitly incorporates electrons, holes and photons in a semiconductor microcavity. Furthermore, we exploit a mapping between the 2D harmonic oscillator and the 2D hydrogen atom that allows us to efficiently solve the problem numerically for the entire Rydberg series as well as for the ground-state exciton. In contrast to previous approaches, we can readily obtain the real-space exciton wave functions and we show how they shrink in size with increasing magnetic field, which mirrors their increasing interaction energy and oscillator strength. We compare our theory with recent experiments on exciton-polaritons in GaAs heterostructures in an external magnetic field and we find excellent agreement with the measured polariton energies. Crucially, we are able to capture the observed light-induced changes to the exciton in the regime of very strong light-matter coupling where a perturbative coupled oscillator description breaks down. Our work can guide future experimental efforts to engineer and control Rydberg excitons and exciton-polaritons in a range of 2D materials.