Nonlinear optical response and exciton dephasing in quantum dots

TL;DR

This paper microscopically calculates the full time-dependent four-wave mixing polarization in quantum dots, revealing how acoustic phonon-assisted transitions cause different exciton dephasing times, explaining the observed double-exponential decay in photon echo signals.

Contribution

It introduces a microscopic calculation of four-wave mixing polarization considering phonon-assisted transitions, explaining exciton dephasing behavior in quantum dots.

Findings

Different dephasing times for exciton states cause double-exponential decay.

Acoustic phonon-assisted transitions significantly influence exciton coherence.

The model matches experimental photon echo decay observations.

Abstract

The full time-dependent four-wave mixing polarization in quantum dots is microscopically calculated, taking into account acoustic phonon-assisted transitions between different exciton states of the dot. It is shown that quite different dephasing times of higher exciton states in pancake anisotropic InGaAs quantum dots are responsible for the experimentally observed [1] double-exponential decay in the photon echo signal.