Phonon impact on optical control schemes of quantum dots: The role of quantum dot geometry and symmetry

TL;DR

This paper investigates how quantum dot geometry and symmetry affect phonon interactions during optical control, showing that lens-shaped dots can be modeled as spherical for phonon influence but symmetry breaking impacts phonon emission patterns.

Contribution

It demonstrates that lens-shaped quantum dots can be mapped to spherical models for phonon influence and provides a method to reproduce spectral densities using simple spherical models.

Findings

Lens-shaped dots can be exactly mapped to spherical models for phonon influence.

Breaking spherical symmetry affects phonon emission directionality.

Spectral densities of complex dots can be approximated by spherical models.

Abstract

Phonons strongly influence the optical control of semiconductor quantum dots. When modeling the electron-phonon interaction in several theoretical approaches the quantum dot geometry is approximated by a spherical structure, though typical self-assembled quantum dots are strongly lens-shaped. By explicitly comparing simulations of a spherical and a lens-shaped dot using a well-established correlation expansion approach we show that indeed lens-shaped dots can be exactly mapped to a spherical geometry when studying the phonon influence on the electronic system. We also give a recipe to reproduce spectral densities from more involved dots by rather simple spherical models. On the other hand, breaking the spherical symmetry has a pronounced impact on the spatio-temporal properties of the phonon dynamics. As an example we show that for a lens-shaped quantum dot the phonon emission is strongly concentrated along the direction of the smallest axis of the dot which is important for the use of phonons for the communication between different dots.