  A field in the vacuum state, which is in principle separable, can evolve to
an entangled state in a dynamical gravitational collapse. We will study,
quantify, and discuss the origin of this entanglement, showing that it could
even reach the maximal entanglement limit for low frequencies or very small
black holes, with consequences in micro-black hole formation and the final
stages of evaporating black holes. This entanglement provides quantum
information resources between the modes in the asymptotic future (thermal
Hawking radiation) and those which fall to the event horizon. We will also show
that fermions are more sensitive than bosons to this quantum entanglement
generation. This fact could be helpful in finding experimental evidence of the
genuine quantum Hawking effect in analog models.
