--- res: bibo_abstract: - Finding a feasible scheme for testing the quantum mechanical nature of the gravitational interaction has been attracting an increasing level of attention. Gravity mediated entanglement generation so far appears to be the key ingredient for a potential experiment. In a recent proposal [D. Carney et al., PRX Quantum 2, 030330 (2021)] combining an atom interferometer with a low-frequency mechanical oscillator, a coherence revival test is proposed for verifying this entanglement generation. With measurements performed only on the atoms, this protocol bypasses the need for correlation measurements. Here, we explore formulations of such a protocol, and specifically find that in the envisioned regime of operation with high thermal excitation, semiclassical models, where there is no concept of entanglement, also give the same experimental signatures. We elucidate in a fully quantum mechanical calculation that entanglement is not the source of the revivals in the relevant parameter regime. We argue that, in its current form, the suggested test is only relevant if the oscillator is nearly in a pure quantum state, and in this regime the effects are too small to be measurable. We further discuss potential open ends. The results highlight the importance and subtleties of explicitly considering how the quantum case differs from the classical expectations when testing for the quantum mechanical nature of a physical system.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Onur foaf_name: Hosten, Onur foaf_surname: Hosten foaf_workInfoHomepage: http://www.librecat.org/personId=4C02D85E-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0002-2031-204X bibo_doi: 10.1103/PhysRevResearch.4.013023 bibo_issue: '1' bibo_volume: 4 dct_date: 2022^xs_gYear dct_isPartOf: - http://id.crossref.org/issn/2643-1564 dct_language: eng dct_publisher: American Physical Society@ dct_title: Constraints on probing quantum coherence to infer gravitational entanglement@ ...