Geometric multipartite entanglement from gravitational particle production

TL;DR

This paper investigates the generation of genuine multipartite entanglement during inflation through gravitational particle production, using a geometric measure called Entanglement Distance, and explores how this entanglement depends on inflationary parameters.

Contribution

It introduces a novel approach to quantify multipartite entanglement during inflation using the Entanglement Distance and analyzes its dependence on inflationary scales and squeezing.

Findings

Infrared cutoff dominates entanglement in negligible squeezing limit

Multipartite entanglement signatures can emerge during late inflation stages

Dependence of entanglement on inflationary momentum scales

Abstract

We explore novel generation of genuine multipartite entanglement within gravitational particle production processes during inflationary stages. To this end, we focus on perturbative production mechanisms, considering a non-minimally coupled scalar inflaton field with quartic self-coupling potential and computing probability amplitudes arising from its gravitational interaction with background perturbations. The corresponding entanglement amount is quantified using the recently proposed Entanglement Distance, that provides a \emph{geometric interpretation of particle entanglement, in terms of the Fubini-Study metric}. We observe that, in the limit of negligible squeezing, the total amount of entanglement is dominated by the infrared cutoff scale, in agreement with previous studies analyzing the von Neumann entropy within bipartite scenarios. We then show that \emph{non-negligible multipartite entanglement signatures may emerge across inflation, even during the latest stages of slow-roll}, highlighting their dependence on inflationary momentum scales. Generalizations to regimes with non-negligible squeezing, cubic non-Gaussianities, additional spectator fields and possible observational signatures are also discussed.