Entanglement creation between two causally-disconnected objects

TL;DR

This paper provides an exact analysis of how quantum entanglement can be generated between two causally disconnected accelerated detectors interacting with a quantum field, revealing conditions for entanglement creation and its finite lifetime.

Contribution

It offers the first exact solutions for entanglement dynamics of accelerated detectors, clarifying when and how entanglement can be generated without direct interaction.

Findings

Entanglement can be created under specific initial conditions and acceleration parameters.

Entanglement lasts only for a finite duration before vanishing.

High acceleration and strong coupling prevent entanglement due to dominant local vacuum fluctuations.

Abstract

We study the full entanglement dynamics of two uniformly accelerated Unruh-DeWitt detectors with no direct interaction in between but each coupled to a common quantum field and moving back-to-back in the field vacuum. For two detectors initially prepared in a separable state our exact results show that quantum entanglement between the detectors can be created by the quantum field under some specific circumstances, though each detector never enters the other's light cone in this setup. In the weak coupling limit, this entanglement creation can occur only if the initial moment is placed early enough and the proper acceleration of the detectors is not too large or too small compared to the natural frequency of the detectors. Once entanglement is created it lasts only a finite duration, and always disappears at late times. Prior result by Reznik derived using the time-dependent perturbation theory with extended integration domain is shown to be a limiting case of our exact solutions at some specific moment. In the strong coupling and high acceleration regime, vacuum fluctuations experienced by each detector locally always dominate over the cross correlations between the detectors, so entanglement between the detectors will never be generated.