On-demand confinement of semiconductor excitons by all-optical control

TL;DR

This paper introduces an all-optical method to dynamically confine semiconductor excitons using laser-induced charge patterning, enabling flexible trapping geometries without complex nano-fabrication.

Contribution

It presents a novel optical technique for exciton confinement in semiconductors, bypassing traditional nano-fabrication methods and allowing in-situ control of exciton transport and trapping.

Findings

Successful optical trapping of exciton gases at low temperatures.

Ability to create arbitrary confinement geometries via laser shaping.

Potential to study quantum correlations in exciton gases.

Abstract

In condensed-matter physics, remarkable advances have been made with atomic systems by establishing a thorough control over cooling and trapping techniques. In semiconductors, this method may also provide a deterministic approach to reach the long standing goal of harnessing collective quantum phenomena with exciton gases. While long-lived excitons are simply cooled to very low temperatures using cryogenic apparatus, engineering confining potentials has been a challenging task. This degree of control was only achieved recently with devices realized by highly demanding nano-fabrication processes. Here, we demonstrate an alternative to this technology and show how a proper optical excitation allows to manipulate in-situ the exciton transport. Our approach is based on the optically controlled injection and spatial patterning of charges trapped in a field-effect device. Thus, electric field gradients are created and implement microscopic traps or anti-traps for the excitons dipole. Accordingly, any confinement geometry can be realized by shaping the spatial profile of a laser excitation. Hence, we succeed in trapping exciton gases in a density range where quantum correlations are predicted at our very low bath temperature.