290S/290K Quantum Materials Seminar speaker Junyeong Ahn (Harvard), Wednesday, January 18, 2023 at 2 pm in Physics South 402

Time/Venue Wednesday, January 18 at 2:00 pm Pacific Time in Physics South 402 and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09
Meeting ID: 995 2349 9113 Passcode: 600704
Host Joel Moore
Title Quantum geometry: Quantum route to optical properties of materials
Abstract The discoveries of a larger number of quantum materials in recent years raise the question of how to employ them in scientific research and technological applications. Designing quantum material properties on demand is a big challenge. Toward this goal, a crucial preliminary step is to identify which key characteristic property of the quantum wave functions relates to the target physical response property. One exciting direction emerging in the field of topological materials is to use the geometry of quantum wave functions – the so-called quantum geometry. This approach has been successful in characterizing various novel electric properties of materials. In this seminar, I will first explain why quantum geometry is a natural concept for characterizing the quantum-ness of response properties. I will then explain a major issue of applying the idea of quantum geometry to resonant optical responses of materials and talk about our resolution to the issue by focusing on electric-dipole transitions. Finally, I will talk about intriguing optical electromagnetic multipole responses beyond electric-dipole transitions due to quantum geometry.