2020/11/25(Wed) 11:00 -12:00 五樓第一會議室 5F, 1st Meeting Room
Title
Symmetry and Topology in Quantum Matter
Speaker
Dr. Chang-Tse Hsieh (Special Postdoctoral Researcher, Quantum Matter Theory Research Team and Condensed Matter Theory Laboratory RIKEN)Abstract
Every physicist knows the importance of symmetry in physics.
Symmetry in nature can be broken in (at least) three different ways:
explicitly, spontaneously, and anomalously; understanding the latter two ways of symmetry breaking has been leading to significant developments in modern physics. For example, the Landau-Ginzburg-Wilson paradigm developed around mid-20th century guides the classification of conventional phases of condensed matter, such as magnets, crystals, and superfluids, based on types of spontaneous symmetry breaking (SSB). However, the discovery of quantum Hall effects in the '80s and of topological insulators even more recently shows the existence of phases outside the framework of SSB, and it has been realized that the interplay between symmetry and topology is in general more subtle and a much richer phenomenology than previously thought can result. On the other hand, quantum anomalies—occurring when symmetries are broken by quantum effects—were initially studied in high energy physics, such as the chiral anomaly in the understanding of pion decays and the parity anomaly from a fundamental field-theory viewpoint, but they have recently been known to play an important role in condensed matter physics, as, for example, the above two kinds of anomalies can also emerge in Weyl semimetals and on the surface of topological insulators, respectively. In this talk, I will speak about quantum mechanical aspects of symmetry and topology in phases of matter, as well as their applications to quantum many-body and strongly correlated systems.
Language
演講語言 (Language): in English