Bound polariton states in the Dicke-Ising model

TL;DR

This paper investigates how cavity quantum electrodynamics can induce bound polariton states in the Dicke-Ising model, revealing cavity-induced localization of spin excitations and their persistence in finite systems.

Contribution

It provides an exact analysis of bound polariton states in the Dicke-Ising model, highlighting cavity-induced localization effects and conditions for their existence.

Findings

Cavity can localize spin excitations, forming bound polaritons.

Bound states exist under specific conditions derived in the study.

Effects are observable in finite systems via exact diagonalization.

Abstract

We present a study of hybrid light-matter excitations in cavity QED materials using the Dicke-Ising model as a theoretical framework. Leveraging linear response theory, we derive the exact excitations of the system in the thermodynamic limit. Our results demonstrate that the cavity can localize spin excitations, leading to the formation of bound polaritons, where the cavity acts as an impurity of the two-excitation band, localizing spin-wave pairs around single-spin domains. We derive the condition for the existence of these bound states and discuss its satisfiability in different regimes. Finally, we show that these effects persist in finite systems using exact-diagonalization calculations.