About the talk

While the dispersion relation in band structures has long been regarded as a fundamental property of electrons in solids, the geometric structure of Bloch wave functions, encoded in the quantum geometric tensor, has recently emerged as a key ingredient of quantum materials. 
We present a unified perspective linking quantum geometry and many-body instabilities in interacting electron systems. We demonstrate that the quantum metric directly controls electronic instabilities, giving rise to ferromagnetism, odd-parity multipole order, and spin-triplet superconductivity. We further reveal its crucial role in the optical responses of superconductors and derive anomalous scaling laws for the superfluid weight of geometric origin.

These results establish a general framework in which quantum geometry serves as a predictive principle for emergent orders and provides a means of identifying exotic superconductors such as twisted multilayer graphene.

About the speaker

Youichi Yanase received his PhD in Science from Kyoto University in 2001 and spent nine years as an assistant professor at the University of Tokyo. After five and a half years at Niigata University, he returned to Kyoto University in 2015. Since 2020, he has been a professor in the Condensed Matter Theory Group at Kyoto University. His group’s research interests include superconductivity and magnetism with exotic symmetry and topology, nonreciprocal responses in quantum materials, and quantum geometry in condensed matter physics.