Unruh effect without trans-horizon entanglement

TL;DR

This paper demonstrates that the Unruh effect persists even with a boundary mirror, indicating it does not solely rely on entanglement between Rindler regions and suggesting a different source of entropy.

Contribution

It shows the Unruh effect remains with a boundary mirror, challenging the view that it depends on entanglement, and proposes Shannon entropy as a key factor.

Findings

Unruh effect persists with a reflecting boundary.

Unruh-DeWitt detector transition rates are unchanged.

Entropy in the Unruh effect may be Shannon entropy, not entanglement entropy.

Abstract

We estimate the transition rates of a uniformly accelerated Unruh-DeWitt detector coupled to a quantum field with reflecting conditions on a boundary plane (a "mirror"). We find that these are essentially indistinguishable from the usual Unruh rates, viz. that the Unruh effect persists in the presence of the mirror. This shows that the Unruh effect is not merely a consequence of the entanglement between left and right Rindler quanta in the Minkowski vacuum. Since in this setup the state of the field in the Rindler wedge is pure, we argue furthermore that the relevant entropy in the Unruh effect cannot be the von Neumann entanglement entropy. We suggest, in alternative, that it is the Shannon entropy associated with Heisenberg uncertainty.