Fluctuation and Commensurability Effect of Exciton Density Wave

TL;DR

This paper investigates the behavior of exciton density waves in coupled quantum wells, focusing on their fluctuation suppression at specific wavelengths and the role of commensurability effects observed experimentally and through simulations.

Contribution

It demonstrates control over the instability wavelength and reveals the fluctuation and commensurability effects in exciton density waves, supported by experimental and numerical evidence.

Findings

Fluctuations are suppressed at commensurate wavelengths.

Observation of fluctuation and commensurability effects.

Numerical simulations support experimental results.

Abstract

At low temperatures, indirect excitons formed at the in-plane electron-hole interface in a coupled quantum well structure undergo a spontaneous transition into a spatially modulated state. We report on the control of the instability wavelength, measurement of the dynamics of the exciton emission pattern, and observation of the fluctuation and commensurability effect of the exciton density wave. We found that fluctuations are strongly suppressed when the instability wavelength is commensurate with defect separation along the exciton density wave. The commensurability effect is also found in numerical simulations within the model describing the exciton density wave in terms of an instability due to stimulated processes.