Entangled Z bosons in Higgs decays confirm quantum links at the electroweak scale

Physicists with CERN's ATLAS collaboration found strong evidence that Z bosons produced in Higgs decays remain quantum-entangled, rejecting a nonentangled alternative at 4.7 sigma (just shy of the 5-sigma discovery threshold). By analyzing the Z bosons’ spin states via four-lepton decays and angular distributions, the result supports Standard Model predictions and demonstrates entanglement at the electroweak scale with massive, short-lived particles. This extends collider tests of quantum information to new regimes and could sharpen future precision tests as more Run 3 and High-Luminosity LHC data become available.