Dephasing in Quantum Dots: Quadratic Coupling to Acoustic Phonons

TL;DR

This paper develops a microscopic theory for optical transitions in quantum dots, revealing how quadratic phonon coupling causes temperature-dependent broadening of the zero-phonon line, with a numerically exact solution for the polarization.

Contribution

It introduces a quadratic phonon coupling into the independent Boson model and provides a numerically exact solution for the interband polarization in quantum dots.

Findings

Quadratic phonon coupling causes temperature-dependent broadening.

The model extends the standard linear coupling approach.

A numerically exact solution for polarization is achieved.

Abstract

A microscopic theory of optical transitions in quantum dots with carrier-phonon interaction is developed. Virtual transitions into higher confined states with acoustic phonon assistance add a quadratic phonon coupling to the standard linear one, thus extending the independent Boson model. Summing infinitely many diagrams in the cumulant, a numerically exact solution for the interband polarization is found. Its full time dependence and the absorption lineshape of the quantum dot are calculated. It is the quadratic interaction which gives rise to a temperature-dependent broadening of the zero-phonon line, being here calculated for the first time in a consistent scheme.