Loss of quantum coherence through scattering off virtual black holes

TL;DR

This paper explores how quantum fields may lose coherence due to scattering off virtual black holes, using a semi-classical model to suggest potential effects of quantum gravity on quantum coherence.

Contribution

It introduces a qualitative approach to study quantum coherence loss via scattering off virtual black holes using the $C$ metric background.

Findings

Finite particles at infinity in the vacuum state.

Loss of quantum coherence observed in the semi-classical model.

Challenges previous claims about particle number at infinity.

Abstract

In quantum gravity, fields may lose quantum coherence by scattering off vacuum fluctuations in which virtual black hole pairs appear and disappear. Although it is not possible to properly compute the scattering off such fluctuations, we argue that one can get useful qualitative results, which provide a guide to the possible effects of such scattering, by considering a quantum field on the $C$ metric, which has the same topology as a virtual black hole pair. We study a scalar field on the Lorentzian $C$ metric background, with the scalar field in the analytically-continued Euclidean vacuum state. We find that there are a finite number of particles at infinity in this state, contrary to recent claims made by Yi. Thus, this state is not determined by data at infinity, and there is loss of quantum coherence in this semi-classical calculation.