Quantifying Entanglement in the Solid State using Neutrons

Developed model-independent approach for entanglement quantification in quantum spin systems, using inelastic neutron scattering (INS) and density matrix renormalization group (DMRG) calculations. This work lays the foundation for a general entanglement detection protocol for quantum spin systems, which is needed to identify quantum materials suitable for new applications such as topological quantum computing.

High-resolution INS measurements are carried out on Cs₂CoCl₄, a realization of the XXZ S=1/2 spin chain, where entanglement is controlled using the magnetic field, to detect entanglement witnesses (EWs), including quantum Fisher information (QFI). Our experimental results are validated by DMRG calculations. QFI is found to be a particularly robust experimental probe of entanglement, characterizing a field-induced quantum phase transition in Cs₂CoCl₄ and thermal entanglement in KCuF₃.   DOI: 10.1103/PhysRevLett.127.037201  DOI: 10.1103/PhysRevB.103.224434