Decoherence of massive superpositions induced by coupling to a quantized gravitational field

TL;DR

This paper explores how coupling to a quantized gravitational field can cause decoherence in massive quantum superpositions, comparing it with other decoherence mechanisms and discussing experimental distinctions.

Contribution

It provides a simple calculation illustrating gravitationally-induced decoherence and discusses how to differentiate it from other decoherence sources experimentally.

Findings

Gravitational coupling can induce decoherence similar to other environmental interactions.

Decoherence due to gravity may be indistinguishable from classical dephasing in some cases.

Experimental methods can potentially discriminate between different decoherence mechanisms.

Abstract

We present a simple calculation leading to the quantum gravitationally-induced decoherence of a spatial superposition of a massive object in the linear coupling regime. The point of this calculation is to illustrate that the gravitationally-induced collapse could be of the same origin as any other collapse, i.e. due to the entanglement between the system (here a massive object) and its environment (in this case gravity, but it could well be the electromagnetic or any other field). We then point out that, in some cases, one has to be careful when concluding that matter-wave interference of large masses (to be quantified) would be prevented by their coupling to the gravitational field. We discuss how to experimentally discriminate between decoherence due to entanglement, decoherence due to classical dephasig as well as a genuine collapse of quantum superpositions (if such a process exists at all).