Cosmological implications of quantum entanglement in the multiverse

TL;DR

This paper investigates how quantum entanglement between causally disconnected universes in the multiverse affects observable cosmological phenomena, suggesting potential experimental tests through analysis of vacuum fluctuation spectra.

Contribution

It introduces a framework for analyzing quantum entanglement effects between universes and predicts observable signatures in the vacuum fluctuation spectrum.

Findings

Entangled universes alter the vacuum fluctuation spectrum.

Non-entangled states produce scale-dependent modulations.

Potential for experimental detection of multiverse entanglement.

Abstract

We explore the cosmological implications of quantum entanglement between two causally disconnected universes in the multiverse. We first consider two causally separated de Sitter spaces with a state which is initially entangled. We derive the reduced density matrix of our universe and compute the spectrum of vacuum fluctuations. We then consider the same system with an initially non-entangled state. We find that scale dependent modulations may enter the spectrum for the case of initially non-entangled state due to quantum interference. This gives rise to the possibility that the existence of causally disconnected universes may be experimentally tested by analyzing correlators in detail.