Scale invariance and universality in a cold gas of indirect excitons

TL;DR

This paper explains why independent clouds of cold dipolar excitons in quantum wells exhibit similar thermodynamic behavior, attributing it to a universal scaling law that governs their condensation regardless of disorder.

Contribution

It introduces a theoretical framework showing that a specific scaling rule causes the critical temperature for exciton condensation to be universal across different traps.

Findings

Condensation starts at the same critical temperature in all traps.

Scaling parameters are insensitive to disorder due to reduced dimensionality.

Universal thermodynamic behavior observed in exciton clouds.

Abstract

We address theoretically the puzzling similarity observed in the thermodynamic behaviour of independent clouds of cold dipolar excitons in coupled semiconductor quantum wells. We argue that the condensation of self-trapped exciton gas starts at the same critical temperature in all traps due to the specific scaling rule. As a consequence of the reduced dimensionality of the system, the scaling parameters appear to be insensitive to disorder.