Correlations in a two-dimensional Bose gas with long range interactions

TL;DR

This paper investigates how two-dimensional dipolar excitons exhibit strong correlations and transition from quantum Bose liquid behavior to classical liquid behavior as their concentration increases, with implications for measuring interactions via luminescence shifts.

Contribution

It provides a theoretical analysis of correlation effects in 2D dipolar excitons across different densities, highlighting the transition from quantum to classical liquid regimes.

Findings

At low densities, excitons form a strongly correlated Bose liquid.

High densities suppress quantum coherence, leading to classical liquid behavior.

Interaction energy and luminescence blue shift serve as indicators of correlations.

Abstract

We study the correlations of two-dimensional dipolar excitons in coupled quantum wells with a dipole -- dipole repulsive interaction. We show that at low concentrations, the Bose degeneracy of the excitons is accompanied by strong multi-particle correlations and the system behaves as a Bose liquid. At high concentration the particles interaction suppresses quantum coherence and the system behaves similar to a classical liquid down to a temperature lower than typical for a Bose gas. We evaluate the interaction energy per particle and the resulting blue shift of the exciton luminescence that is a direct tool to measure the correlations. This theory can apply to other systems of bosons with extended interaction.