**Quantum materials under the nonlinear electromagnetic spotlight **

Close to large masses, the geometry of space-time warps, bending the light trajectory and leading to dramatic phenomena like black holes and gravitational waves. The quantum world of electrons likewise has a geometrical structure, constructed from electronic quantum wave functions. Such a quantum geometrical structure, studied as quantum metric and Berry curvature, can reshape an electron’s behaviors in nontrivial ways [1]. Quantum geometry also has a deep relation with topological phases of matter, which have taken center stage in condensed matter over the past decade. Although many topological phases have been experimentally discovered in quantum materials, the understanding of how bulk quantum geometry is manifest in material properties has remained limited. In this talk, I will show several examples in 2D layered materials how quantum geometry can strongly modify the electronic response to external electromagnetic waves and give rise to a wide range of previously unexplored nonlinear responses [2-3].

[1] arXiv: 2103.03269 (2021)

[2] *Nature* 578, 545 (2020)

[3] *Nature* 565, 337 (2019)

Host: Mengkun Liu