Gravitational decoherence by the apparatus in the quantum-gravity induced entanglement of masses

TL;DR

This paper investigates how gravitational interactions with laboratory apparatus can cause decoherence in experiments designed to test the quantum nature of gravity, analyzing conditions under which entanglement persists despite such decoherence.

Contribution

It models the apparatus as quantum systems and evaluates how gravitational decoherence affects entanglement in proposed quantum gravity experiments.

Findings

Decoherence magnitude can be estimated for specific experimental setups.

Entanglement can survive under certain conditions despite gravitational decoherence.

Conditions for evading decoherence depend on system parameters and coupling strengths.

Abstract

One of the outstanding questions in modern physics is how to test whether gravity is classical or quantum in a laboratory. Recently there has been a proposal to test the quantum nature of gravity by creating quantum superpositions of two nearby neutral masses, close enough that the quantum nature of gravity can entangle the two quantum systems, but still sufficiently far away that all other known Standard Model interactions remain negligible. However, the mere process of preparing superposition states of a neutral mass (the light system), requires the vicinity of laboratory apparatus (the heavy system). We will suppose that such a heavy system can be modelled as another quantum system; since gravity is universal, the lighter system can get entangled with the heavier system, providing an inherent source of gravitational decoherence. In this paper, we will consider two light and two heavy quantum oscillators, forming pairs of probe-detector systems, and study under what conditions the entanglement between two light systems evades the decoherence induced by the heavy systems. We conclude by estimating the magnitude of the decoherence in the proposed experiment for testing the quantum nature of gravity.