Würzburg ToCoTronics Colloquium

Entanglement is a key resource for quantum information. In condensed matter systems, it is thought to be notoriously difficult to define, detect, or quantify entanglement. I will discuss the potential of the “strange metal” state to make progress. Strange metal behavior – best known as a linear-in-temperature electrical resistivity at low temperatures instead of the normal Fermi liquid square-in-temperature one – occurs across many classes of quantum materials [1,2]. Its full understanding is a key open challenge. Heavy fermion compounds are particularly versatile model materials for studying this physics: they are comparatively simple, clean, and highly tunable, and several characteristics beyond linear-in-temperature resistivity have already been identified. Furthermore, first materials are now available as MBE-grown thin films, offering new possibilities [3,4]. I will highlight the first glimps at entanglement properties obtained in a heavy fermion strange metal using the quantum Fisher information analysis of inelastic neutron scattering data [5] and also discuss implications for a recently discovered emergent topological semimetal [6].

[1] S. Paschen & Q. Si, Nat. Rev. Phys. 3, 9 (2021).
[2] J. G. Checkelsky, B. A. Bernevig, P. Coleman, Q. Si, & S. Paschen, Nat. Rev. Mater., published online, Feb. 20 (2024).
[3] L. Prochaska et al., Science 367, 285 (2020).
[4] L. Chen et al., Science 382, 907 (2023).
[5] F. Mazza et al., arXiv:2403.12779 (2024).
[6] D. M. Kirschbaum, L. Chen et al., arXiv:2404.15924 (2024).