Entangling Power of an Expanding Universe

TL;DR

This paper demonstrates that entanglement properties of quantum fields can serve as indicators of spacetime curvature, distinguishing between Minkowski and de Sitter universes through their differing entangling capabilities.

Contribution

It introduces a method to detect spacetime curvature by analyzing entanglement swapping and detector responses in different cosmological backgrounds.

Findings

Single detector in de Sitter responds thermally like in Minkowski

Entanglement between detectors differs in Minkowski and de Sitter universes

Entangling power reveals spacetime curvature differences

Abstract

We show that entanglement can be used to detect spacetime curvature. Quantum fields in the Minkowski vacuum are entangled with respect to local field modes. This entanglement can be swapped to spatially separated quantum systems using standard local couplings. A single, inertial field detector in the exponentially expanding (de Sitter) vacuum responds as if it were bathed in thermal radiation in a Minkowski universe. We show that using two inertial detectors, interactions with the field in the thermal case will entangle certain detector pairs that would not become entangled in the corresponding de Sitter case. The two universes can thus be distinguished by their entangling power.