Physicists unlock way to measure quantum entanglement inside real-world materials By decoding neutron data, scientists can now put a number on entanglement inside complex materials. Scientists have always wondered whether ordinary materials are also secretly held together by quantum connections. Until now, there seems to be no way to answer this question. However, recently, a team of researchers has demonstrated a technique that can directly detect entanglement inside solids. So instead of guessing or relying purely on theory, scientists can now directly measure how entangled a material is—an essential step for designing better quantum devices. Moreover, according to the researchers, their technique works even when there is no perfect theoretical model of the material, and the sample is not pure (which is often the case in real-world materials). “We’ve found that it works 100 percent,” Allen Scheie, one of the researchers and a condensed matter physicist at Los Alamos National Laboratory in New Mexico, said. Turning neutron echoes into a map of entanglement The problem scientists faced wasn’t a lack of theory but a lack of tools. Traditional methods like Bell tests can confirm entanglement between a few particles, but they break down when dealing with the trillions of interacting particles inside a solid. Materials are messy, complex, and often imperfect, making it extremely difficult to tell whether entanglement is present, let alone measure how much of it exists. The researchers tackled this by refining neutron scattering, a technique that has been around since the 1950s. In simple terms, they fired neutrons at a material and observed how those neutrons bounced off. These scattered neutrons carry subtle fingerprints of what’s happening inside a material—how atoms are arranged and how their quantum properties behave. However, the real breakthrough came from combining this old tool with a newer concept called quantum Fisher