Interaction-driven transport of dark excitons in 2D semiconductors with phonon-mediated optical readout

TL;DR

This paper demonstrates that dark excitons in 2D semiconductors can diffuse over several micrometers, enabling long-range, robust transport suitable for quantum and classical information applications through phonon-mediated optical readout.

Contribution

It introduces a new mechanism for long-range dark exciton transport in 2D materials, leveraging phonon interactions for optical readout, which was not previously demonstrated.

Findings

Dark excitons can diffuse over several micrometers.

Transport is robust across non-uniform samples.

Optical readout is mediated by chiral phonons.

Abstract

The growing field of quantum information technology requires propagation of information over long distances with efficient readout mechanisms. Excitonic quantum fluids have emerged as a powerful platform for this task due to their straightforward electro-optical conversion. In two-dimensional transition metal dichalcogenides, the coupling between spin and valley provides exciting opportunities for harnessing, manipulating and storing bits of information. However, the large inhomogeneity of single layers cannot be overcome by the properties of bright excitons, hindering spin-valley transport. Nonetheless, the rich band structure supports dark excitonic states with strong binding energy and longer lifetime, ideally suited for long-range transport. Here we show that dark excitons can diffuse over several micrometers and prove that this repulsion-driven propagation is robust across non-uniform samples. The long-range propagation of dark states with an optical readout mediated by chiral phonons provides a new concept of excitonic devices for applications in both classical and quantum information technology.