Entanglement Structure in Expanding Universes

Understand

We investigate entanglement of a quantum field in de Sitter spacetime using a particle detector model.

• By considering the entanglement between two comoving detectors interacting with a scalar field, it is possible to detect the entanglement of the scalar field by swapping it to detectors.
• For the massless minimal scalar field, we find that the entanglement between the detectors cannot be detected when their physical separation exceeds the Hubble horizon scale.
• This behavior supports the appearance of the classical nature of quantum fluctuations generated during the inflationary era.