Polariton condensation and lasing in optical microcavities - the decoherence driven crossover

TL;DR

This paper investigates how decoherence affects polariton condensation and lasing in microcavities, revealing a crossover from condensate to laser behavior driven by decoherence strength and excitation density.

Contribution

It introduces a self-consistent model of decoherence effects on polariton systems, demonstrating a crossover from condensate to laser regimes similar to gapless superconductivity.

Findings

Decoherence broadens and suppresses the energy gap in the system.

A transition from polariton condensate to laser occurs with increasing decoherence.

The crossover is analogous to Abrikosov-Gor'kov theory of gapless superconductivity.

Abstract

We explore the behaviour of a system which consists of a photon mode dipole coupled to a medium of two-level oscillators in a microcavity in the presence of decoherence. We consider two types of decoherence processes which are analogous to magnetic and non-magnetic impurities in superconductors. We study different phases of this system as the decoherence strength and the excitation density is changed. For a low decoherence we obtain a polariton condensate with comparable excitonic and photonic parts at low densities and a BCS-like state with bigger photon component due to the fermionic phase space filling effect at high densities. In both cases there is a large gap in the density of states. As the decoherence is increased the gap is broadened and suppressed, resulting in a gapless condensate and finally a suppression of the coherence in a low density regime and a laser at high density limit. A crossover between these regimes is studied in a self-consistent way analogous to the Abrikosov and Gor'kov theory of gapless superconductivity.