Quantum or classical? A reinvestigation of the Quasi 1D Ising Systems CsCoX₃ (X = Cl, Br)

The presence of entanglement signifies a unique aspect of quantum materials which is absent in classical systems. Experimental determination of entanglement has remained one of the most highly sought protocols for probing the quantum behavior in solid state systems. Recent breakthroughs in measuring entanglement witnesses via spectroscopic measurements have opened an avenue toward quantifying entanglement present in quantum systems. Most notably these witnesses focused on a quantum limit Heisenberg spin chain system, where a close theoretical and experimental comparison could be made. In this talk I reinvestigate the canonical quasi-1D Ising systems CsCoX₃ (X = Br,Cl) using state of the art neutron spectrometers. A careful comparison with theory and estimates of entanglement witnesses within these systems is discussed as well as their sensitivity to experimental factors.