Accuracy of the quantum regression theorem for photon emission from a quantum dot

TL;DR

This paper evaluates the accuracy of the quantum regression theorem in predicting photon emission properties from quantum dots, revealing it tends to overestimate environmental effects compared to exact methods.

Contribution

It provides a quantitative comparison between the quantum regression theorem and exact path-integral results for photon emission from quantum dots, highlighting limitations of the QRT.

Findings

QRT overestimates environmental influence on photon properties

Path-integral results show more accurate photon emission characteristics

QRT's limitations impact quantum information applications

Abstract

The quantum regression theorem (QRT) is the most-widely used tool for calculating multitime correlation functions for the assessment of quantum emitters. It is an approximate method based on a Markov assumption for the environmental coupling. In this work we quantify properties of photons emitted from a single quantum dot coupled to phonons. For the single-photon purity and the indistinguishability, we compare numerically exact path-integral results with those obtained from the QRT. It is demonstrated that the QRT systematically overestimates the influence of the environment for typical quantum dots used in quantum information technology.