A bstract In our quest to understand the generation of cosmological perturbations, we face
two serious obstacles: we do not have direct information about the environment experienced …

We show how to compute the purity and entanglement entropy for quantum fields in a
systematic perturbative expansion. To that end, we generalize the in-in formalism to non …

Master equations are commonly employed in cosmology to model the effect of additional
degrees of freedom, treated as an “environment”, onto a given “system”. However, they rely …

We investigate quantum decoherence in a class of models which interpolates between
expanding (inflation) and contracting (ekpyrosis) scenarios. For the cases which result in a …

We study Unruh phenomena for a qudit detector coupled to a quantized scalar field,
comparing its response to that of a standard qubit-based Unruh-DeWitt detector. We show …

We revisit the problem of the thermalization process in an entropic formulation for the Unruh-
DeWitt (UDW) detector outside a Schwarzschild black hole. We derive the late-time …

This thesis develops the implementation of Open Effective Field Theories in primordial
cosmology. Offering a unique window onto unknown physics, primordial cosmology faces …

We revisit a simple toy model of two scalar fields in de Sitter space, playing the roles of"
system" and" environment" degrees of freedom, which interact with each other. We show that …

We investigate the one-particle sector for the field-theoretical model of gravitationally
induced decoherence for a scalar field in [1] with a special focus on the renormalisation of …

We consider the coupling of a scalar field to linearised gravity and derive a relativistic
gravitationally induced decoherence model using Ashtekar variables. The model is …