Theory of Bose-Einstein condensation and superfluidity of two-dimensional polaritons in an in-plane harmonic potential

TL;DR

This paper develops a theoretical framework for Bose-Einstein condensation and superfluidity of 2D exciton-polaritons in a harmonic trap, revealing how superfluid and condensate fractions behave as the trap depth varies.

Contribution

It introduces a general method to define the superfluid fraction in a 2D trap using angular momentum representation and analyzes the behavior of condensate and superfluid fractions in different trap regimes.

Findings

Superfluid fraction approaches the 2D Kosterlitz-Thouless limit as the trap becomes shallower.

Condensate fraction approaches zero in the continuum limit for shallow traps.

Provides a theoretical basis for understanding BEC and superfluidity in trapped 2D polariton systems.

Abstract

Recent experiments have shown that it is possible to create an in-plane harmonic potential trap for a two-dimensional (2D) gas of exciton-polaritons in a microcavity structure, and evidence has been reported of Bose-Einstein condensation of polaritons accumulated in this type of trap. We present here the theory of Bose-Einstein condensation (BEC) and superfluidity of the exciton polaritons in a harmonic potential trap. Along the way, we determine a general method for defining the superfluid fraction in a 2D trap, in terms of angular momentum representation. We show that in the continuum limit, as the trap becomes shallower the superfluid fraction approaches the 2D Kosterlitz-Thouless limit, while the condensate fraction approaches zero, as expected.