Amplified entanglement witnessed in a quantum critical metal

Strong correlations in matter promote a landscape of ground states and associated quantum critical points. For metallic systems, there is increasing recognition that the quantum criticality goes beyond the standard Landau framework and, thus, novel means are needed to characterize the quantum critical fluid. Here we do so by studying the entanglement properties near a quantum critical point of a strongly correlated metal. We calculate the mutual information and quantum Fisher information of an Anderson/Kondo lattice model across its Kondo destruction quantum critical point. The quantum Fisher information of the spin degree of freedom peaks at the quantum critical point and indicates a strongly entangled ground state. Our results are supported by the quantum Fisher information extracted from inelastic neutron scattering measurements in quantum critical heavy fermion metals. Our work opens a new avenue to advance the understanding of metallic quantum criticality in a broad range of strongly correlated systems, and points to a new regime of quantum matter to witness amplified entanglement.