Representing an advance for quantum materials, scientists tested the ability of techniques called entanglement witnesses to accurately identify pairs of entangled magnetic particles. Entanglement is when one of the particles mirrors another’s properties and behavior regardless of the distance between them. The research evaluated three entanglement witnesses. Of the three, quantum Fisher information (QFI) performed the best, routinely locating entanglement in complex materials. QFI also differentiated between actual quantum activity and non-quantum activity that can appear quantum due to random thermal motion. The experiments confirmed that entanglement increases as temperature decreases.
The most thorough examination of QFI’s capabilities is also the first to apply the technique to massive solid materials by examining many pairs of entangled spins simultaneously. With QFI, scientists can quickly identify entangled quantum materials such as quantum spin liquids, quantum magnets, and superconductors. Incorporating QFI calculations into future neutron scattering experiments could help research teams characterize even more complex quantum materials.
Because of their neutral charge and nondestructive nature, neutrons provided valuable insights into the properties of two different spin chains. The researchers also ran computational simulations and analyzed data from older experiments conducted at the ISIS Neutron Source and the Institut Laue-Langevin.