Detecting entanglement between a few particles through Bell tests is well established, but extension to many-body systems remains challenging.

In such systems, often only few-body correlation measurements can be carried out that violate Bell inequalities only under several assumptions.

In this work, we demonstrate substantial violation of a Bell inequality for collective measurements on a many-particle system based on majority voting and parity binning. In a proof-of-principle experiment with entangled photons, non-local correlations in clusters up to 41 particle pairs  were detected, opening a path for detecting entanglement in systems of growing complexity.