Single exciton emission from gate-defined quantum dots

TL;DR

This paper demonstrates a novel gate-defined quantum dot platform that can confine and control single long-living indirect excitons, enabling tunable optical and quantum properties for potential quantum information applications.

Contribution

It introduces a new lithographically defined quantum dot system for optically active, voltage-tunable excitons with controllable charge and spin states.

Findings

Discrete emission lines from few excitons due to interexcitonic interactions.

Quantum dot states are tunable by gate voltage.

Magnetic field induces a diamagnetic shift.

Abstract

With gate-defined electrostatic traps fabricated on a double quantum well we are able to realize an optically active and voltage-tunable quantum dot confining individual, long-living, spatially indirect excitons. We study the transition from multi excitons down to a single indirect exciton. In the few exciton regime, we observe discrete emission lines reflecting the interplay of dipolar interexcitonic repulsion and spatial quantization. The quantum dot states are tunable by gate voltage and employing a magnetic field results in a diamagnetic shift. The scheme introduces a new gate-defined platform for creating and controlling optically active quantum dots and opens the route to lithographically defined coupled quantum dot arrays with tunable in-plane coupling and voltage-controlled optical properties of single charge and spin states.