Functional materials Band Drude weight (BDW) Orbital Angular Momentum (OAM) Quantum Metric (QM) Berry Curvature (BC) a b c d ψ(λ+dλ) ψ(λ) Quant. Dist. dΩ Y3 2 Mingu Kang1,2, Sunje Kim3,4,5, Yuting Qian3,4,5, Paul M. Neves1, Linda Ye1, Junseo Jung3,4,5, Denny Puntel6, Federico Mazzola7,8, Shiang Fang1, Chris Jozwiak9, Aaron Bostwick9, Eli Rotenberg9, Jun Fuji7, Ivana Vobornik7, Jae-Hoon Park2,10, Joseph G. Checkelsky1, Bohm-Jung Yang3,4,5, Riccardo Comin1 1 Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA 2 Max Planck POSTECH/Korea Research Initiative, Center for Complex Phase of Materials Pohang, Republic of Korea 3 Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea 4 Center for Theoretical Physics (CTP), Seoul National University, Seoul, Republic of Korea 5 Institute of Applied Physics, Seoul National University, Seoul, Republic of Korea 6 Department of Physics, University of Trieste, Trieste, Italy 7 Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy 8 Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Venice, Italy 9 Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, USA 10 Department of Physics, Pohang University of Science and Technology, Pohang, Republic of Korea e-mail: iordia@snu.ac.kr Acknowledgments M. Kang acknowledges a Kavli Postdoctoral Fellowship from the Kavli Nanoscience Institute at Cornell. Original paper M. Kang et al., Nat. Phys. 21, 110 (2025); DOI: 10.1038/s41567-024-02678-8. Fig. 1 Figure 1. Quantum geometry and experimentally measurable quantities in spin- and polarization-resolved ARPES at Elettra. (a) Real part of the quantum geometric tensor, the quantum metric, which describes the quantum distance between electronic wavefunctions in parameter space. (b) Imaginary part of the quantum geometric tensor, the Berry curvature, which describes the phase information of electronic wavefunctions in parameter space. (c),(d), Experimentally measurable quantities using spin- and polarization-resolved ARPES: the band Drude weight (c) and the orbital angular momentum (d). Band Drude weight and orbital angular momentum construct quasi-quantum geometric tensor, from which we could mathematically reconstruct quantum geometric tensor. Elettra Highlights 2024–2025 15
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