Phonon-Assisted Incoherent Excitation of a Quantum Dot and its Emission Properties

TL;DR

This paper investigates phonon-assisted incoherent excitation of quantum dots, demonstrating efficient excitation via acoustic phonons, analyzing the phonon bath, and exploring emission coherence properties at low temperatures.

Contribution

It introduces a spectrally-detuned laser excitation method mediated by phonons and provides an analytical model predicting broadband incoherent coupling in the strong phonon regime.

Findings

Achieved up to 20% excitation efficiency at 9 K

Mapped the acoustic phonon bath via laser frequency dependence

Developed an analytical model for broadband incoherent coupling

Abstract

We present a detailed study of a phonon-assisted incoherent excitation mechanism of single quantum dots. A spectrally-detuned laser couples to a quantum dot transition by mediation of acoustic phonons, whereby excitation efficiencies up to 20 % with respect to strictly resonant excitation can be achieved at T = 9 K. Laser frequency-dependent analysis of the quantum dot intensity distinctly maps the underlying acoustic phonon bath and shows good agreement with our polaron master equation theory. An analytical solution for the photoluminescence is introduced which predicts a broadband incoherent coupling process when electron-phonon scattering is in the strong phonon coupling (polaronic) regime. Additionally, we investigate the coherence properties of the emitted light and study the impact of the relevant pump and phonon bath parameters.