Pattern Formation as a Signature of Quantum Degeneracy in a Cold Exciton System

TL;DR

This paper proposes that pattern formation due to a Turing instability in a photoexcited electron-hole system can serve as a signature of exciton Bose statistics, revealing quantum degeneracy effects through spatial patterns.

Contribution

It introduces a novel signature of quantum degeneracy in exciton systems via pattern formation driven by stimulated processes near quantum degeneracy.

Findings

Triangular lattice pattern in 2D electron-hole system

Periodic 1D pattern at electron-hole interface

Abrupt (type I) and continuous (type II) transitions

Abstract

The development of a Turing instability to a spatially modulated state in a photoexcited electron-hole system is proposed as a novel signature of exciton Bose statistics. We show that such an instability, which is driven by kinetics of exciton formation, can result from stimulated processes that build up near quantum degeneracy. In the spatially uniform 2d electron-hole system, the instability leads to a triangular lattice pattern while, at an electron-hole interface, a periodic 1d pattern develops. We analyze the mechanism of wavelength selection, and show that the transition is abrupt (type I) for the uniform 2d system, and continuous (type II) for the electron-hole interface.