Measuring the effective phonon density of states of a quantum dot

TL;DR

This paper uses decay-rate measurements of a quantum dot in a photonic crystal cavity to determine the effective phonon density of states, revealing insights into phonon dephasing in solid-state quantum systems.

Contribution

It introduces a microscopic non-Markovian model that accurately describes phonon dephasing and extracts the effective phonon density of states from experimental data.

Findings

Effective phonon density of states matches bulk phonon theory.

Dephasing explained by longitudinal acoustic phonons.

Differences in cavity feeding linked to phonon interactions.

Abstract

We employ detuning-dependent decay-rate measurements of a quantum dot in a photonic-crystal cavity to study the influence of phonon dephasing in a solid-state quantum-electrodynamics experiment. The experimental data agree with a microscopic non-Markovian model accounting for dephasing from longitudinal acoustic phonons, and identifies the reason for the hitherto unexplained difference between non-resonant cavity feeding in different nanocavities. From the comparison between experiment and theory we extract the effective phonon density of states experienced by the quantum dot. This quantity determines all phonon dephasing properties of the system and is found to be described well by a theory of bulk phonons.