The quantum optical description of three experiments involving non-linear optics using a graphical method

TL;DR

This paper presents a graphical method to analyze three quantum optics experiments involving non-linear crystals and interferometers, providing simplified explanations that sometimes differ from original interpretations.

Contribution

It introduces a graphical approach and simplified model to interpret complex quantum optics experiments involving entanglement and non-linear processes.

Findings

Successfully explains experimental results using the graphical method

Highlights differences in interpretation of indistinguishability and entanglement

Provides a simplified framework for understanding quantum optics experiments

Abstract

In this paper we describe and thoroughly discuss three reported experiments in quantum optics (QO) involving interferometers and non-linear crystals. We show that by using a graphical method and an over-simplified model of the parametric down-conversion process, we arrive to explain all the important results reported in the respective papers. Indistinguishability is discussed in the case of separable/non-separable (i.e. entangled) quantum systems and our interpretation is sometimes at variance with the one given by the authors reporting the experiments.