Spectral Line Broadening and Angular Blurring due to Spacetime Geometry Fluctuations

TL;DR

This paper investigates how quantum fluctuations in spacetime geometry can cause spectral line broadening and angular blurring, using Riemann tensor correlations and analyzing effects from graviton states.

Contribution

It introduces a geometrical framework to relate spacetime fluctuations to observable effects and applies it to specific graviton states, highlighting new phenomenological insights.

Findings

Spectral line broadening depends on graviton state properties.

Angular blurring can be quantified via Riemann tensor correlations.

Fluctuations are maximized in squeezed vacuum states.

Abstract

We treat two possible phenomenological effects of quantum fluctuations of spacetime geometry: spectral line broadening and angular blurring of the image of a distance source. A geometrical construction will be used to express both effects in terms of the Riemann tensor correlation function. We apply the resulting expressions to study some explicit examples in which the fluctuations arise from a bath of gravitons in either a squeezed state or a thermal state. In the case of a squeezed state, one has two limits of interest: a coherent state which exhibits classical time variation but no fluctuations, and a squeezed vacuum state, in which the fluctuations are maximized.