spin entanglement witness for quantum gravity

by Anupam Mazumdar (Canadian institute for Theoretical Astrophysics, University of Toronto)

Thursday 12 Nov 2026, 10:00 → 11:00 Europe/Zurich

40/S2-A01 - Salle Anderson (CERN)

Although quantum gravity is theoretically well studied, it has no empirical evidence yet. This makes ``Is gravity quantum?" one of the most important open questions of our time. We have pioneered an ambitious idea, ``spin entanglement witness for quantum gravity," to test the quantum nature of gravity in a lab with my collaborators. It exploits quantum information ideas and combines a quantum spin with cooling/trapping quantum technologies. It is based on entangling two neutral quantum masses solely by their gravitational interaction while all other interactions are mitigated, e.g., electromagnetic (EM) interactions between the masses. It proves the quantum nature of gravity, as classical gravity cannot mediate quantum correlations (entanglement). The potentially realizable protocol requires meeting a rich set of challenges: mitigating the EM interactions and background, creating spatial quantum superpositions for massive objects, and measuring spin correlations to witness the entanglement. We must also protect the quantum superpositions from heating, blackbody radiation, acceleration, seismic, and gravity-gradient noise.