Entangled Detectors Nonperturbatively Harvest Mutual Information

TL;DR

This paper studies how entangled detectors interacting with a quantum field in flat spacetime lose entanglement nonperturbatively, revealing that they can still extract mutual information from the vacuum even as entanglement degrades.

Contribution

It introduces a nonperturbative analysis of entangled detectors in Minkowski spacetime, showing how entanglement degrades with coupling and how mutual information can be extracted from the vacuum.

Findings

Entanglement degrades with increasing coupling strength.

Weakly entangled or separable detectors can extract mutual information from the vacuum.

Communication does not mitigate entanglement degradation, only alters its nature.

Abstract

We investigate how entangled inertial Unruh-DeWitt detectors are affected by interaction with a quantum field using a nonperturbative method. Inertial detectors in a $(3+1)$-dimensional Minkowski spacetime with instantaneous switching ($\delta$-switching) experience degradation of their initial entanglement as their coupling strength with a scalar field increases. Somewhat surprisingly, initially separable or weakly entangled detectors can extract mutual information from the vacuum. We also find that entanglement degradation is not reduced if communication via the field is possible; rather this only changes the manner in which entanglement is degraded.