# Gravitational Decoherence

## TL;DR

This paper reviews gravitational decoherence, exploring how gravity-induced loss of quantum coherence can be experimentally studied through tabletop experiments, models of wave function collapse, and precision gravity measurements.

## Contribution

It surveys existing models of gravitational decoherence, discusses theories where gravity causes wave function collapse, and reviews current experimental efforts in measuring gravity effects on quantum systems.

## Key findings

- Gravitational decoherence can be probed with tabletop experiments.
- Models suggest gravity may induce wave function collapse.
- Current experiments aim for more precise gravity measurements on quantum systems.

## Abstract

We discuss effects of loss of coherence in low energy quantum systems caused by or related to gravitation, referred to as gravitational decoherence. These effects, resulting from random metric fluctuations, for instance, promise to be accessible by relatively inexpensive table-top experiments, way before the scales where true quantum gravity effects become important. Therefore, they can provide a first experimental view on gravity in the quantum regime. We will survey models of decoherence induced both by classical and quantum gravitational fluctuations; it will be manifest that a clear understanding of gravitational decoherence is still lacking. Next we will review models where quantum theory is modified, under the assumption that gravity causes the collapse of the wave functions, when systems are large enough. These models challenge the quantum-gravity interplay, and can be tested experimentally. In the last part we have a look at the state of the art of experimental research. We will review efforts aiming at more and more accurate measurements of gravity (G and g) and ideas for measuring conventional and unconventional gravity effects on nonrelativistic quantum systems.