Strange Metals and Entanglement Witnesses

10.12.2024 13:00 – 14:30

For quantum materials in the quantum information era, some of the outstanding issues are how to use entanglement means to help advance the quantum materials’ understanding and how to identify those with amplified entanglement. Here we focus on strange metals. A notable example occurs in Kondo systems, where the physics of beyond-Landau quantum criticality, through the process of Kondo destruction, results in a complete loss of quasiparticles at the quantum critical point [1]. The presence of critical fluctuations on the entire Fermi surface leads to strange metallicity and causes unconventional superconductivity with elevated transition temperature [1]. At this antiferromagnetic quantum critical point, the charge degrees of freedom also exhibit singular response with dynamical Planckian scaling [2]. This unusual behavior suggests a charge-spin entangled quantum critical fluid, providing direct motivation for using quantum information means to characterize the strange metal state.
We analyze entanglement measures across the beyond-Landau quantum critical point [3]. These include mutual information and quantum Fisher information. The latter reveals amplified multipartite entanglement in the quantum critical fluid. Our results are supported by experiments from heavy fermion strange metals [3]. I will explain how the findings, in addition to pointing to a novel regime of quantum matter for amplified entanglement, shed new light on the nature of the strange metallicity.
[1] H. Hu, L. Chen & Q. Si, Nat. Phys. in press (2024); S. Paschen & Q. Si, Nat. Rev. Phys. 3, 9 (2021); S. Kirchner et al, Rev. Mod. Phys. 92, 011002 (2020); Q. Si et al., Nature 413, 804 (2001).
[2] A. Cai et al., Phys. Rev. Lett. 124, 027205 (2020); L. Prochaska et al., Science 367, 285 (2020).
[3] Y. Fang et al., arXiv:2402.18552 (2024).

Lieu

Bâtiment: Ecole de Physique

Auditoire Stuckelberg

entrée libre