Dynamics of excitons in individual InAs quantum dots revealed in four-wave mixing spectroscopy

TL;DR

This study combines experimental and theoretical four-wave mixing spectroscopy to analyze exciton dynamics in individual InAs quantum dots, revealing detailed coherence and population behaviors influenced by fine-structure splitting and biexciton interactions.

Contribution

It provides a comprehensive analysis of exciton complex dynamics in single quantum dots using polarization-resolved four-wave mixing micro-spectroscopy, including the effects of polarization, pulse areas, and temporal ordering.

Findings

Oscillatory FWM signals governed by fine-structure splitting and biexciton binding energy.

Dynamics depend on polarization configuration, pulse areas, and timing.

FWM spectroscopy effectively characterizes spectral and dynamical properties of single quantum dots.

Abstract

A detailed understanding of the population and coherence dynamics in optically driven individual emitters in solids and their signatures in ultrafast nonlinear-optical signals is of prime importance for their applications in future quantum and optical technologies. In a combined experimental and theoretical study on exciton complexes in single semiconductor quantum dots we reveal a detailed picture of the dynamics employing three-beam polarization-resolved four-wave mixing (FWM) micro-spectroscopy. The oscillatory dynamics of the FWM signals in the exciton-biexciton system is governed by the fine-structure splitting and the biexciton binding energy in an excellent quantitative agreement between measurement and analytical description. The analysis of the excitation conditions exhibits a dependence of the dynamics on the specific choice of polarization configuration, pulse areas and temporal ordering of driving fields. The interplay between the transitions in the four-level exciton system leads to rich evolution of coherence and population. Using two-dimensional FWM spectroscopy we elucidate the exciton-biexciton coupling and identify neutral and charged exciton complexes in a single quantum dot. Our investigations thus clearly reveal that FWM spectroscopy is a powerful tool to characterize spectral and dynamical properties of single quantum structures.