Can gravity link two objects through entanglement, a quantum connection in which the objects share one state even when apart? Many physicists see this as a key sign that gravity itself follows quantum rules. Three researchers now propose an experiment in which a tiny particle, about a micrometer across and levitated in place, would interact through gravity with an array of extremely precise nuclear clocks. The authors argue that the combined effect of many clocks could make such entanglement measurable in a laboratory.
The twist is what the test would probe. Einstein showed that energy adds to mass, so a clock's internal energy should add to its gravitational pull. The authors argue that seeing the entanglement would show that this energy-based mass behaves in a quantum way, which they say no experiment has tested yet. The experiment has not been built, and the paper is a preprint that has not been peer reviewed.
