Quasi-condensation of bilayer excitons in a periodic potential

TL;DR

This paper investigates how excitons in a two-dimensional lattice can form a quasi-condensate under certain conditions, revealing the effects of lattice depth on condensation and the emergence of localized quasi-condensates.

Contribution

It introduces a detailed analysis of exciton behavior in lattice potentials, highlighting the transition from quasi-condensation to localized phases as lattice depth varies.

Findings

Quasi-condensation possible at low lattice depths with small phase-space density.

Increased lattice depth raises the critical phase-space density beyond experimental reach.

Deep lattice potential leads to an array of phase-independent quasi-condensates.

Abstract

We study two-dimensional excitons confined in a lattice potential, for high fillings of the lattice sites. We show that a quasi-condensate is possibly formed for small values of the lattice depth, but for larger ones the critical phase-space density for quasi-condensation rapidly exceeds our experimental reach, due to the increase of the excitons effective mass. On the other hand, in the regime of a deep lattice potential where excitons are strongly localised at the lattice sites, we show that an array of phase-independent quasi-condensates, different from a Mott insulating phase, is realised.