Entanglement negativity in the multiverse

TL;DR

This paper investigates quantum entanglement between causally disconnected regions in the multiverse, focusing on entanglement negativity in de Sitter space, revealing scale-dependent behavior influenced by scalar field mass.

Contribution

It introduces a method to compute entanglement negativity in de Sitter space and analyzes how it varies with scale and field mass, offering insights into multiverse quantum correlations.

Findings

Entanglement negativity qualitatively matches entanglement entropy.

Scale dependence affects entanglement based on observer constraints.

Initial maximal entanglement can increase or decrease on large scales.

Abstract

We explore quantum entanglement between two causally disconnected regions in the multiverse. We first consider a free massive scalar field, and compute the entanglement negativity between two causally separated open charts in de Sitter space. The qualitative feature of it turns out to be in agreement with that of the entanglement entropy. We then introduce two observers who determine the entanglement between two causally disconnected de Sitter spaces. When one of the observers remains constrained to a region of the open chart in a de Sitter space, we find that the scale dependence enters into the entanglement. We show that a state which is initially maximally entangled becomes more entangled or less entangled on large scales depending on the mass of the scalar field and recovers the initial entanglement in the small scale limit. We argue that quantum entanglement may provide some evidence for the existence of the multiverse.