Finite-size effects in two-photon correlations of exciton Bose-Einstein condensates

Accessing two-photon statistics via Hunbary Brown and Twiss (HBT)-type measurements is essential for investigations of excitonic Bose-condensates. In this paper we make use of quantum hydrodynamics in order to study the finite-size impact on the two-photon emission intensity of a 2D condensate of excitons. We use the developed approach to calculate the two-photon decay time of exciton condensate in GaAs quantum wells and MoS$_2$ bilayers. We demonstrate that the registered signal scales on the sample size in a qualitatively different manner than the Bogoliubov theory predicts.