Hong–Ou–Mandel interference of more than ten indistinguishable atoms

When two indistinguishable bosons interfere at a beam splitter, they exit through the same output port. This quantum effect, known as Hong–Ou–Mandel interference, underpins many protocols in quantum information. It also generalizes to larger numbers of identical particles, for which interference produces characteristic many-body patterns. So far, experiments have observed the many-particle regime mainly in photonic platforms with unavoidable loss, and atomic realizations have remained challenging. Here we demonstrate Hong–Ou–Mandel interference with up to 12 indistinguishable neutral atoms in a system with negligible loss. Single-particle counting reveals parity oscillations, a bunching envelope and genuine multipartite entanglement, which are defining features of the multiparticle Hong–Ou–Mandel effect. Using the generated quantum states, we demonstrate metrological sensitivities that scale with the number of particles according to the Heisenberg limit. Our technique can be extended to larger ensembles, with wide-ranging applications from high-precision atom interferometry to multiparticle Bell tests. Hong–Ou–Mandel interference has been difficult to extend to ensembles of many massive particles. Measurements on up to 12 neutral atoms now exhibit characteristic multiparticle interference pattern with single-atom resolution and negligible loss.