Amplified multipartite entanglement witnessed in a quantum critical metal

TL;DR

This paper demonstrates that quantum Fisher information peaks at the quantum critical point in a strange metal, revealing strongly entangled ground states and providing a new quantum information approach to understanding metallic quantum criticality.

Contribution

It introduces the use of quantum Fisher information to characterize entanglement in quantum critical metals, supported by experimental neutron scattering data.

Findings

Quantum Fisher information peaks at the critical point.

Strong entanglement in the ground state near criticality.

Experimental validation with neutron scattering data.

Abstract

Strong correlations in matter promote a landscape of quantum phases and associated quantum critical points. For metallic systems, there is increasing recognition that the quantum criticality goes beyond the Landau framework and, thus, novel means are needed to characterize the quantum critical fluid. Here we do so by studying an entanglement quantity, the quantum Fisher information, in a strange metal system, focusing on the exemplary case of an Anderson/Kondo lattice model near its Kondo destruction quantum critical point. The spin quantum Fisher information 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 heavy fermion metals. Our work elucidates the loss of quasiparticles in strange metals, opens a quantum information avenue to advance the understanding of metallic quantum criticality in a broad range of strongly correlated systems, and points to a novel regime of quantum matter to realize amplified entanglement.