Polariton condensation with localised excitons and propagating photons

TL;DR

This paper estimates the condensation temperature of microcavity polaritons considering their internal structure, revealing different regimes depending on density and Rabi splitting, and calculates related excitation spectra.

Contribution

It introduces a generalized Dicke model to analyze polariton condensation, accounting for internal structure effects at higher densities.

Findings

Condensation temperature scales linearly with density at low densities.

At high densities, the structure of polaritons influences the condensation temperature.

The excitation spectrum relates to observable luminescence and absorption spectra.

Abstract

We estimate the condensation temperature for microcavity polaritons, allowing for their internal structure. We consider polaritons formed from localised excitons in a planar microcavity, using a generalised Dicke model. At low densities, we find a condensation temperature T_c \propto \rho, as expected for a gas of structureless polaritons. However, as T_c becomes of the order of the Rabi splitting, the structure of the polaritons becomes relevant, and the condensation temperature is that of a B.C.S.-like mean field theory. We also calculate the excitation spectrum, which is related to observable quantities such as the luminescence and absorption spectra.