Entanglement between the future and past in the quantum vacuum

TL;DR

This paper demonstrates that the quantum vacuum exhibits entanglement between the future and past light cones, with potential experimental detection via a thermal response of a specific detector.

Contribution

It reveals a novel form of vacuum entanglement between future and past regions, extending the understanding of quantum field correlations.

Findings

Vacuum is entangled between future and past light cones.

A detector can exhibit a thermal response to this entanglement.

Experimental detection of this effect is feasible.

Abstract

We note that massless fields within the future and past light cone may be quantized as independent systems. We show that the vacuum is an entangled state of these systems, exactly mirroring the known entanglement between the spacelike separated Rindler wedges. We describe a detector which exhibits a thermal response to the vacuum when switched on at t=0. The feasibility of experimentally detecting this effect is discussed.