Repulsive Gravitational Force as a Witness of the Quantum Nature of Gravity

We show that a single spatially superposed 'source' mass acting on a 'probe' matter wavepacket can reveal the quantum nature of the gravitational field. For this we use a specific state preparation and measurement of the superposed source mass, including a postselection, which altogether results in a repulsive gravitational force on the probe particle. A classical gravitational field can never lead to repulsion, as the effect requires quantum interference of two distinct states of gravity. We also present a calculation in the Heisenberg picture under the formalism of weak values that illustrates how repulsion is achieved. Finally, we estimate the range of parameters (masses and the spatio-temporal extent of interference) for which the experiment is feasible.

Source: arXiv:2602.12266v1 - http://arxiv.org/abs/2602.12266v1 PDF: https://arxiv.org/pdf/2602.12266v1 Original Link: http://arxiv.org/abs/2602.12266v1