Models of coherent exciton condensation

TL;DR

This paper reviews theoretical models of exciton and polariton condensates, exploring their coherence, crossover behaviors, and connections to laser physics, highlighting the fundamental understanding of exciton condensation over the past decades.

Contribution

It provides a comprehensive overview of the theoretical frameworks and concepts underlying exciton and polariton condensates, emphasizing coherence and crossover phenomena.

Findings

Coherence in ground state wavefunctions explained

BCS to Bose crossover in excitons and polaritons analyzed

Relationship between condensates and lasers discussed

Abstract

That excitons in solids might condense into a phase-coherent ground state was proposed about 40 years ago, and has been attracting experimental and theoretical attention ever since. Although experimental confirmation has been hard to come by, the concepts released by this phenomenon have been widely influential. This tutorial review discusses general aspects of the theory of exciton and polariton condensates, focussing on the reasons for coherence in the ground state wavefunction, the BCS to Bose crossover(s) for excitons and for polaritons, and the relationship of the coherent condensates to standard lasers.