On the quantum nature of primordial black holes in inflationary cosmology

In this thesis, we provide a quantum description to the formation of primordial black holes tackling the conventional methods of describing CMB anisotropies and formation of black holes in a semi-classical way. These primordial black holes arrive in nature at a very early stage of the universe soon after the end of inflation. We adopt a quan- tum field perspective to make an assumption of the size of these primordial black holes. Furthermore, we define the vacuum fluctuations of the Bunch-Davies type that arise during the inflationary epoch as a scalar perturbation field in curved space. Using the particle occupation of the vacuum state, we correlate the findings with a corpuscular theory of gravity to quantify our claim. This thesis works as a toy model to quantize primordial black holes from scalar perturbations left from inflation, therefore, this work can be adopted by various inflationary scenarios and similar early universe mechanisms that give rise to the same scale-invariant metric perturbations.