Spatial mapping of quantum-dot dynamics across multiple timescales at low temperature using remote asynchronous optical sampling

TL;DR

This paper introduces a novel asynchronous optical sampling method using a fiber-delivered frequency comb to simultaneously observe quantum dot dynamics across multiple timescales and spatial locations, significantly reducing measurement time.

Contribution

The authors develop a fiber-based asynchronous optical sampling technique that enables rapid, spatially-resolved measurement of quantum dot dynamics across multiple timescales.

Findings

Spatial mapping of quantum dot dynamics over 1x1 mm^2 area at 441 points in 30.1 minutes

Simultaneous resolution of quantum beats and relaxation lifetimes at each point

Measurement efficiency improved from over 12 days to about half an hour

Abstract

Quantum dots (QDs) offer significant potential for applications in quantum information and optoelectronic devices; however, conventional time-resolved spectroscopy cannot generally simultaneously extract both long-lived relaxation dynamics and short-lived quantum beats from ensemble measurements. This limitation arises from the inherent trade-off between temporal resolution and total acquisition time. Here, we demonstrate that asynchronous optical sampling based on a fiber-delivered frequency comb enables simultaneous observation of QD dynamics across multiple timescales. By integrating a galvanometric scanner, we achieve spatial mapping over a $1 \times 1$-\si{\milli\meter}$^2$ area at 441 discrete points in 30.1~min, a measurement that would otherwise require more than 12~days. At each location, both quantum beats and relaxation lifetimes are resolved, giving physical insights into QD ensembles that were previously inaccessible and paving the way for rapid feedback in device fabrication.