Entanglement of the Vacuum between Left, Right, Future, and Past: The Origin of Entanglement-Induced Quantum Radiation

TL;DR

This paper explores the entanglement structure of the vacuum state across different spacetime regions and its role in quantum radiation, extending previous understanding to more general spacetimes.

Contribution

It extends the analysis of vacuum entanglement to Kasner spacetimes and clarifies the origin of quantum radiation from accelerated detectors.

Findings

Vacuum entanglement exists between multiple spacetime regions.

Quantum radiation arises from entanglement in accelerated frames.

In 2D massless case, entanglement persists without radiation.

Abstract

The Minkowski vacuum state is expressed as an entangled state between the left and right Rindler wedges when it is constructed on the Rindler vacuum. In this paper, we further examine the entanglement structure and extend the expression to the future (expanding) and past (shrinking) Kasner spacetimes. This clarifies the origin of the quantum radiation produced by an Unruh--DeWitt detector in uniformly accelerated motion in the four-dimensional Minkowski spacetime. We also investigate the two-dimensional massless case where the quantum radiation vanishes but the same entanglement structure exists.