Naoto Nagaosa (Tokyo/RIKEN) gave a talk on "Geometry in optical responses of quantum materials." Geometry and topology provide new insight into optical responses of solids and are of interdisciplinary interest in physics. After an excellent review on this topic made over the past decade, Naoto mainly discussed (i) shift current in noncentrosymmetric quantum materials driven by Berry phases, and (ii) Riemannian geometry in nonlinear optical responses. About 50 physicists from various fields have joined the seminar and enjoyed fruitful discussions during and after the seminar.

Reported by Hidetoshi Taya


  1. J. Ahn and N. Nagaosa, Theory of optical responses in clean multi-band superconductors, Nature Communications 12, 1617 (2021), doi: 10.1038/s41467-021-21905-x
  2. T. Morimoto and N. Nagaosa, Topological nature of nonlinear optical effects in solids, Science Advances, Vol 2, Issue 5 (2016), doi: 10.1126/sciadv.1501524
  3. J. Ahn, G.Y, Guo and N.Nagaosa, Low-Frequency Divergence and Quantum Geometry of the Bulk Photovoltaic Effect in Topological Semimetals, Physical Review X, Volume 10, Issue 4 (2020), doi: 10.1103/PhysRevX.10.041041
  4. J. Ahn, G.Y, Guo, N.Nagaosa, A. Vishwanath, Nature Phys. To appear