On two recent proposals for witnessing nonclassical gravity

Abstract

Two very similar proposals have been made recently for witnessing nonclassical features of gravity, by Bose et al. and by Marletto and Vedral. However, while these proposals are asserted to be very general, they are in fact based on a very strong claim: that quantum systems cannot become entangled via a classical intermediary. We point out that the support provided for this claim is only applicable to a very limited class of quantum-classical interaction models, corresponding to Koopman-type dynamics. We show that the claim is also valid for mean-field models, but that it is contradicted by explicit counterexamples based on the configuration-ensemble model. Thus, neither proposal provides a definitive test of nonclassical gravity.

New references added, minor corrections. Close to final version

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• A Spin Entanglement Witness for Quantum Gravity
• Gravitationally-induced entanglement between two massive particles is sufficient evidence of quantum effects in gravity
• Measurement Analysis and Quantum Gravity
• Consistent classical and quantum mixed dynamics
• Nonquantum Gravity
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Cited by in corpus (7)

• Decoherence effects in non-classicality tests of gravity
• Witnessing the non-classical nature of gravity in the presence of unknown interactions
• Gravity-induced entanglement in optomechanical systems
• Nonlinear Schrödinger equations and generalized Heisenberg uncertainty principle violating the principle of estimation independence
• Generation of entanglement between two laser pulses through gravitational interaction
• Essential role of destructive interference in the gravitationally induced entanglement
• Entanglement and quantum teleportation under superposed gravitational fields