Freiburg 2024 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 15: Optomechanics

Q 15.5: Talk

Tuesday, March 12, 2024, 12:15–12:30, HS 1015

Classical phase-space model for gravity-mediated entanglement — •Marta Maria Marchese, Martin Plávala, Matthias Kleinmann, and Stefan Nimmrichter — Universität Siegen, Siegen, Germany

Whether gravity is fundamentally quantum or not is still a debated question. On one side, there are several well-established quantum-gravity theories, on the other, there are semi-classical descriptions that treat the gravity field as a classical measurement-feedback channel. The lack of experimental evidence leaves the problem still unresolved, but experiments with massive levitated particles have been proposed: witnessing entanglement generated by the gravitational interaction between two masses in a matter-wave interferometer is claimed to probe the quantum nature of the gravitational field. Here, we argue that such a scheme is not sufficient to rule out all possible classical descriptions of gravity. Indeed, one can achieve the same entanglement built up through a classical evolution of the Wigner function of the two gravitationally interacting masses, making use of a second-order approximation of the Newtonian potential. This suggests that alternative experimental schemes be developed to test the quantum nature of gravity.

Keywords: Gravity; Matter-wave interferometry; Wigner function; Entanglement; Levitated optomechanics