A note on initial state entanglement in inflationary cosmology

Understand

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.