Extra High Energy Theory Seminar: Patricia Ribes Metidieri

Title: Inflation does not create entanglement in local observables

Abstract: Inflation is often argued to generate quantum entanglement between cosmological perturbations with opposite wavenumbers. This seems to be in tension with the standard treatment of cosmological perturbations, where their quantum state is replaced by a classical probability distribution, effectively removing all quantum effects.

In this talk, I argue that this apparent tension can be alleviated by examining how entanglement is distributed among local observables accessible within our universe. I show that although each local degree of freedom becomes entangled with the rest of the field by an amount set by the spacetime curvature, this entanglement is highly delocalized, and effectively acts as noise for entanglement between local observables. As a result, entanglement between observables within the observable universe is strongly suppressed, helping to explain the apparent classicality of cosmological perturbations.