Entanglement test to witness quantum nature of gravity in a lab

by Mazumdar Anupam (University of Groningen)

Friday 13 Mar 2026, 16:00 → 17:00 Europe/Rome

Aula Conversi (Dip. di Fisica - Edificio G. Marconi)

Quantum field theories and classical general relativity accurately model all observations to date. Although quantum gravity has been theoretically much studied, it still lacks empirical evidence. This makes “is spacetime/gravity quantum?” one of our most important open questions. I have pioneered an ambitious idea with my collaborators, “spin entanglement witness for quantum gravity,” to test the quantum nature of gravity in a lab. It exploits ideas from quantum information and combines a quantum spin with cooling and trapping 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 realisable 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 quantum superpositions from heating, recoil, blackbody radiation, acceleration, seismic and gravity-gradient noise.