Dynamical formation and interaction-induced stabilization of dark condensates of dipolar excitons

TL;DR

This paper demonstrates how a dense Bose-Einstein condensate of dipolar excitons forms dynamically in dark states and remains stable due to strong interactions, revealing new collective phenomena in non-equilibrium quantum systems.

Contribution

It introduces a model for non-equilibrium dynamics of coupled dark and bright exciton condensates, explaining the formation and stabilization of dark condensates in dipolar excitons.

Findings

Dark exciton condensates form via a dynamical transition to long-lived states.

Strong dipole-dipole interactions stabilize high-density dark quantum liquids.

The model reproduces step-like exciton density dependence on pump power and temperature.

Abstract

The formation of a dense Bose-Einstein condensate in dark spin states of two-dimensional dipolar excitons is shown to be driven by a dynamical transition to the long-lived dark states. The condensate is stabilized by strong dipole-dipole interactions up to densities high enough for a dark quantum liquid to form. The persistence of dark condensation was observed in recent experiments. A model describing the non-equilibrium dynamics of externally driven coupled dark and bright condensates reproduces the step-like dependence of the exciton density on the pump power or on temperature. This unique condensate dynamics demonstrates the possibility of observing new unexpected collective phenomena in coupled condensed Bose systems, where the particle number is not conserved.