Deep‑underground test finds no radiation signal from gravity‑induced decoherence

# What the experiment tested Physicists tested a specific decades‑old idea that tiny, unavoidable fluctuations in spacetime — predicted in a version of Károlyházy's model — would randomly accelerate charged particles. Those accelerations would produce an extremely faint electromagnetic radiation background. Detecting that radiation would be a measurable signature that gravity‑related spacetime noise destroys quantum superpositions as systems grow larger.

# How the team searched for the signal

# Main result No radiation signal matching the prediction appeared in the residual data. The absence of the predicted emission means that this version of gravity‑induced decoherence is not supported by the measurement. The team published the result in the New Journal of Physics in June 2026.

# What this rules out and what it leaves open This experiment eliminates one clear, specific formulation of gravity‑driven decoherence that would have produced a detectable electromagnetic signature. It does not show that gravity plays no role in decoherence in general. Other gravity‑related mechanisms, different parameter ranges, or models that do not predict the same radiation signature remain viable. The result narrows the parameter space theorists must consider and provides quantitative constraints that future proposals must respect.

# Why the setting and detector matter Searching for the predicted signal requires extreme suppression of ordinary radiation sources. Gran Sasso's rock overburden lowers cosmic‑ray fluxes, and the copper/lead shielding reduces local radioactive backgrounds. Using a high‑purity germanium crystal gives good sensitivity to low‑energy electromagnetic emissions. Those elements combined make the setup one of the quietest available for this kind of rare‑signal search.

# Who led the effort The experiment involved the VIP Collaboration at the National Laboratory of Frascati (INFN‑LNF). Catalina Curceanu, director of research and spokesperson for the collaboration, is quoted in the report connected to the Foundational Questions Institute (FQXi) about the importance of testing gravity‑related decoherence ideas.

# Practical takeaway for researchers The null measurement provides an empirical boundary: theories that predict the specific Károlyházy‑style radiation must be revised or discarded. Future experimental work can push sensitivity further, test different model variants, or seek alternative observable consequences of gravity interacting with quantum systems. The result refocuses theoretical and experimental effort by excluding a clear, testable proposal.

# Broader context The experiment sits among several recent tests probing how quantum mechanics and gravity intersect. Some work looks for phase shifts in falling quantum particles, others put larger objects into superposition. This study contributes by converting an abstract gravity‑fluctuation idea into a concrete, testable radiation signature and then checking that prediction in one of Earth's quietest laboratories.