A note on initial state entanglement in inflationary cosmology

TL;DR

This paper explores how initial entanglement between scalar fields in de Sitter space influences the vacuum fluctuation spectrum, offering a new interpretation and exact calculations that challenge previous expectations of oscillatory features.

Contribution

It introduces a novel interpretation of initial state entanglement effects and derives an exact power spectrum for entangled scalar fields in inflationary cosmology.

Findings

Oscillatory spectrum is unlikely without specific Bogoliubov coefficient choices.

Constructs initial entangled states using Bogoliubov transformations and squeezed states.

Provides exact power spectrum calculations for entangled fields in de Sitter space.

Abstract

We give a new interpretation of the effect of initial state entanglement on the spectrum of vacuum fluctuations. We consider an initially entangled state between two free massive scalar fields in de Sitter space. We construct the initial state by making use of a Bogoliubov transformation between the Bunch-Davies vacuum and a four mode squeezed state, and then derive the exact power spectrum for one of the scalar fields. We demonstrate that an oscillatory spectrum hardly appears for the initially entangled state unless an ad hoc absolute value of the Bogoliubov coefficients is chosen.