Proving quantum entanglement – when a magnetic particle’s spin mirrors another’s properties and behavior regardless of their distance from each other – has been a major challenge in quantum information science. The team studied an entanglement witness, or method for identifying entanglement, called QFI  (quantum Fisher information) by applying the witness to neutron scattering experiments at the Spallation Neutron Source, a Department of Energy user facility at DOE’s Oak Ridge National Laboratory. Because of their neutral charge and nondestructive nature, the neutrons provided valuable insights into the properties of two different spin chains, or linear lines of connected spins within quantum materials. To validate their results, the researchers also ran computational simulations and analyzed data from older experiments conducted at the ISIS Neutron Source and the Institut Laue-Langevin.