Mollow "quintuplets" from coherently-excited quantum dots

TL;DR

This paper models and experimentally confirms the emergence of a five-peak Mollow quintuplet spectrum in coherently excited quantum dots with anisotropic exchange splitting, extending the classic triplet spectrum.

Contribution

The paper introduces a polaron master equation model for two-exciton pumping and demonstrates the first experimental observation of Mollow quintuplets in quantum dots.

Findings

Observation of five-peak Mollow spectra in quantum dots

Good agreement between theoretical model and experimental data

Extension of Mollow triplet to quintuplet due to anisotropic exchange splitting

Abstract

Charge-neutral excitons in semiconductor quantum dots have a small finite energy separation caused by the anisotropic exchange splitting. Coherent excitation of neutral excitons will generally excite both exciton components, unless the excitation is parallel to one of the dipole axes. We present a polaron master equation model to describe two-exciton pumping using a coherent continuous wave pump field in the presence of a realistic anisotropic exchange splitting. We predict a five-peak incoherent spectrum, thus generalizing the Mollow triplet to become a Mollow quintuplet. We experimentally confirm such spectral quintuplets for In(Ga)As quantum dots and obtain very good agreement with theory.