Decoherence in semiconductor cavity QED systems due to phonon scattering

TL;DR

This paper studies how electron-phonon interactions affect the coherence and indistinguishability of single photons emitted from semiconductor cavity QED systems, highlighting the importance of non-Markovian effects and the validity of perturbation theory.

Contribution

It introduces a second order perturbation theory to analyze phonon effects in semiconductor cavity QED systems and compares it with exact methods to determine its validity.

Findings

Non-Markovian effects significantly influence photon coherence.

Perturbation theory's validity depends on cavity decay rates.

Conditions for applying Markovian approximation are established.

Abstract

We investigate the effect of electron-phonon interactions on the coherence properties of single photons emitted from a semiconductor cavity QED system, i.e. a quantum dot embedded in an optical cavity. The degree of indistinguishability, governing the quantum mechanical interference between two single photons, is calculated as a function of important parameters describing the cavity QED system and the phonon reservoir, e.g. cavity quality factor, light-matter coupling strength, temperature and phonon lifetime. We show that non-Markovian effects play an important role in determining the coherence properties for typical parameter values and establish the conditions under which a Markovian approximation may be applied. The calculations are performed using a recently developed second order perturbation theory, the limits of validity of which are established by comparing to an exact diagonalization approach. We find that for large cavity decay rates the perturbation theory may break down.