Probing quantum geometry with optics

CFM COLLOQUIUM SERIES

The quantum geometry of electron states in crystals gives rise to fascinating phenomena, such as topological (quantized) responses. Currently, there is great interest in devising experimental protocols for directly probing the Berry curvature, quantum metric, and orbital moment of Bloch electrons [*]. Central to this effort is the notion that ground-state quantum geometry can be related to the excitation spectrum via optical sum rules. In this talk I will review those ideas, from their early inception to recent developments.

Image borrowed from S. Kim et al., Science 388, 1050 (2025).