Probing single charge fluctuations in a semiconductor with laser spectroscopy on a quantum dot

TL;DR

This paper uses laser spectroscopy on quantum dots to detect and analyze single charge fluctuations in semiconductors, revealing the main sources of charge noise and enabling near-transform-limited optical linewidths.

Contribution

It introduces a method to probe local charge fluctuations at the single-charge level using quantum dot spectroscopy, improving understanding of charge noise sources.

Findings

Quantum dots are sensitive to single charge changes in their environment.

Charge noise sources in optical field-effect devices are identified and quantified.

Near-transform-limited quantum dot optical linewidths are achieved.

Abstract

We probe local charge fluctuations in a semiconductor via laser spectroscopy on a nearby self-assembled quantum dot. We demonstrate that the quantum dot is sensitive to changes in the local environment at the single charge level. By controlling the charge state of localized defects, we are able to infer the distance of the defects from the quantum dot with +-5 nm resolution. The results identify and quantify the main source of charge noise in the commonly-used optical field-effect devices. Based on this understanding we achieve routinely close-totransform-limited quantum dot optical linewidths.