Green's functions technique for calculating the emission spectrum in a quantum dot-cavity system

TL;DR

This paper presents a Green's functions method as an efficient and accurate alternative to the quantum regression theorem for computing emission spectra in quantum dot-cavity systems, simplifying numerical calculations.

Contribution

It introduces a Green's functions approach for emission spectrum calculation in open quantum systems, overcoming limitations of the quantum regression theorem.

Findings

Green's functions technique shows improved accuracy.

The method is more efficient computationally.

It simplifies the calculation process for emission spectra.

Abstract

We introduce the Green's functions technique as an alternative theory to the quantum regression theorem formalism for calculating the two-time correlation functions in open quantum systems. In particular, we investigate the potential of this theoretical approach by its application to compute the emission spectrum of a dissipative system composed by a single quantum dot inside of a semiconductor cavity. We also describe a simple algorithm based on the Green's functions technique for calculating the emission spectrum of the quantum dot as well as of the cavity which can easily be implemented in any numerical linear algebra package. We find that the Green's functions technique demonstrates a better accuracy and efficiency in the calculation of the emission spectrum and it allows to overcome the inherent theoretical difficulties associated to the direct application of the quantum regression theorem approach.