Underground detector finds no sign that gravity erases quantum superpositions
An experiment deep beneath Italy's Gran Sasso mountain searched for a faint radiation signal predicted by a theory linking gravity to the collapse of quantum states. After 62 days of measurements with a shielded germanium detector, no such signal appeared, weakening that explanation for why quantum effects vanish in the macroscopic world.
The experiment ran for 62 days using a germanium detector heavily shielded against background radiation, positioned beneath 1.4 kilometers of rock at Italy's Gran Sasso National Laboratory. The search targeted faint electromagnetic emissions that would arise if spacetime fluctuations, as proposed by Frigyes Károlyházy in the 1960s and later refined by Angelo Bassi and colleagues, were disrupting quantum superpositions of charged particles.
No such signal was detected, weakening this gravitational explanation for decoherence. The findings appeared in the New Journal of Physics in June 2026, with the work led by Catalina Curceanu of the VIP Collaboration at INFN-LNF. The null result narrows the possible mechanisms behind the transition from quantum to classical behavior.
This result could influence how physicists approach the quantum-classical boundary, potentially redirecting research toward alternative decoherence mechanisms. It may also shape future experimental designs, as null results help refine theoretical models. Society's broader interest lies in fundamental science: understanding why our macroscopic world behaves classically could eventually inform technologies relying on quantum effects, though practical applications remain distant and speculative.