  The quantum origin of cosmological primordial perturbations is a cornerstone
framework in the interplay between gravity and quantum physics. In this paper
we study the mutual information between two spatial regions in a
radiation-dominated universe filled by a curvature perturbation field in a
squeezed state. We find an enhancement with respect to the usual mutual
information of the Minkowski vacuum due to momentum modes affected by particle
production during inflation. This result supports our previous claim of the
existence of long-range correlations between Primordial Black Holes (PBH) at
formation during the radiation era.
