Assoc. Prof. Menderes Işkın
Koç University
“Cooper pairing, flat-band superconductivity and quantum geometry”
Abstract
The so-called quantum geometric tensor is one of the basic components of the geometric quantum mechanics, i.e., a complex valued matrix whose real and imaginary parts are known, respectively, as the Fubini-Study or the quantum metric tensor and Berry curvature. As the naming suggests, the quantum metric is a measure of the distance between two nearby quantum states, characterized by the local geometry of the complex quantum space. In contrast, the Berry curvature corresponds to the emergent gauge field in the quantum space, the total flux of which is related to the global topology of the quantum states, e.g. the Chern number. In striking contrast to the physical importance of the Berry curvature and quantum topology that has been put forward in the past two decades or so, there is relatively much slower progress in showing the possible connection between a physical system and its quantum metric and quantum geometry. In this talk I will present an exact relation between the inverse of the effective-mass tensor of the lowest bound states and the quantum-metric tensor of the underlying Bloch states in a multiband Hubbard model, and discuss its ramifications in flat-band superconductors.
I acknowledge funding from US Air Force Office of Scientific Research (AFOSR) Grant No. FA8655-24-1-7391.
Associate Professor Menderes Işkın received his bachelor’s degree from Bilkent in 2002 and PhD from GaTech in 2007. He worked 2 years as a guest researcher at NIST before joining Koc University in 2009. His research on condensed atomic and molecular physics has received several national awards including TUBITAK’s Incentive Award in Basic Sciences in 2012.
Date : October 30, 2024 Wednesday
Time : 15:30
Place : SA-240
All interested are cordially invited.