Unraveling the mesoscopic character of quantum dots in nanophotonics

TL;DR

This paper develops a microscopic theory explaining deviations from point-dipole models in quantum dots within nanophotonics, highlighting the role of structural inhomogeneities and mesoscopic currents, supported by experimental data.

Contribution

It introduces a new microscopic model accounting for mesoscopic effects in quantum dots, advancing understanding beyond traditional point-dipole approximations.

Findings

Large circular quantum currents inside dots cause deviations from point-dipole behavior.

Experimental data shows significant variation in multipolar moments across emission spectra.

The model aligns well with spectroscopic observations of quantum dots.

Abstract

We provide a microscopic theory for semiconductor quantum dots that explains the pronounced deviations from the prevalent point-dipole description that were recently observed in spectroscopic experiments on quantum dots in photonic nanostructures. At the microscopic level the deviations originate from structural inhomogeneities generating a large circular quantum current density that flows inside the quantum dot over mesoscopic length scales. The model is supported by the experimental data, where a strong variation of the multipolar moments across the emission spectrum of quantum dots is observed. Our work enriches the physical understanding of quantum dots and is of significance for the fields of nanophotonics, quantum photonics, and quantum-information science, where quantum dots are actively employed.