SPICE Workshop on Quantum materials and quantum information science May 19th - 21st, 2026
Simiao Si
In this talk, I will address strange metals and how measurable quantum entanglement properties deepen their understanding. Using the heavy fermion systems as a notable example, I will show how the theoretical description in terms of Kondo destruction not only provides the understanding of the T-linear resistivity but also leads to an emerging profile of strange metallicity in general [1]. The accompanying salient features include dynamical Planckian scaling, jump of Fermi surface across the quantum critical point (QCP) and the loss of quasiparticles at the QCP. Despite the QCP being antiferromagnetic, the charge degrees of freedom also exhibit a singular response [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 both mutual information and quantum Fisher information [3]. The quantum Fisher information reveals amplified multipartite entanglement in the quantum critical fluid. Our theoretical results are supported by experiments in quantum critical heavy fermion metals [3]. Our findings, in addition to implicating a novel regime of quantum matter for amplified entanglement, provide a positive characterization about the loss of quasiparticles and, thus, a deepened understanding of strange metallicity. Prospects for future studies, including in the context of correlated flat band systems [4], will be briefly discussed.
[1] L. Chen, H. Hu, A. Cai & Q. Si, to be published (2026); H. Hu, L. Chen & Q. Si, Nat. Phys. 20, 1863 (2024); 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., Nat. Commun. 16, 2498 (2025).
[4] L. Chen et al., Nat. Commun. 15, 5242 (2024); L. Chen et al., arXiv:2307.09431; H. Hu et al., Sci. Adv. 9, eadg0028 (2023); F. Xie et al., Phys. Rev. Research 7, L022061 (2025).