Partially suppressed long-range order in the Bose-Einstein condensation of polaritons

TL;DR

This paper develops a kinetic theory for polariton Bose-Einstein condensation, revealing how quantum fluctuations cause partial suppression of long-range order and depend on system size.

Contribution

It introduces a model that accurately describes the impact of quantum fluctuations on long-range order in polariton condensates.

Findings

Quantum fluctuations significantly deplete the condensate.

Long-range order is partially suppressed due to fluctuations.

Finite system size influences the degree of order.

Abstract

We adopt a kinetic theory of polariton non-equilibrium Bose-Einstein condensation, to describe the formation of off-diagonal long-range order. The theory accounts properly for the dominant role of quantum fluctuations in the condensate. In realistic situations with optical excitation at high energy, it predicts a significant depletion of the condensate caused by long-wavelength fluctuations. As a consequence, the one-body density matrix in space displays a partially suppressed long-range order and a pronounced dependence on the finite size of the system.