Abstract
Symmetry plays a central role in our understanding of quantum many-body systems. In the first part of this talk, I will provide an overview of my past work, illustrating how spontaneous symmetry breaking offers a predictive framework for organizing phases and determining their low-energy excitations, and how symmetry serves as a guiding principle for classifying and diagnosing topological phases of matter.
I will then turn to my recent research on frustration-free quantum systems --- tractable yet surprisingly rich models that uncover new theoretical insights. I will describe a universal lower bound on their spectral gap, an unexpected correspondence between quantum and classical dynamics, and the resulting implications for the dynamical critical exponent governing classical Ising dynamics.
I will conclude with a forward-looking perspective, using insights from frustration-free systems as a stepping stone toward broader studies of open quantum systems and quantum information theory.
Haruki Watanabe is an Associate Professor of Applied Physics at the University of Tokyo, where he has led a research group as a principal investigator since 2016. His research aims to uncover universal principles governing quantum many-body systems, focusing on how symmetry informs their phases and responses. He has made notable contributions to the theory of Nambu–Goldstone modes, symmetry indicators in topological materials, and frustration-free quantum systems. He received his Ph.D. from UC Berkeley under Ashvin Vishwanath and held a Pappalardo Fellowship at MIT. His work has been recognized with the New Horizons in Physics Prize, the Yukawa Memorial Prize, and a Commendation from Japan’s Minister of Education, among others. He also received teaching awards for his enthusiastic lecture.