Theory of Parametric Down Conversion in Bulk Non-Linear Crystals: An Introduction

Parametric Down Conversion (PDC) is a very important resource for what concern the development of quantum technologies and for experiments about foundation of quantum mechanics. The interest about this phenomenon is due to the fact that photons emitted by PDC are quantum correlated in many parameters and it is possible to use the PDC to produce states of light with strong non-classical behaviour. The aim of this paper is provide an extensive review on the theory of Parametric Down Conversion whit particular emphasis for what concern the case of Spontaneous Parametric Down Conversion (SPDC) in bulk non-linear crystals.