[PAST EVENT] Physics Colloquium
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- Open to the public
In history, solid states are characterized by the symmetries they respect and also by those they break. Not only does this idea distinguish graphite and diamond, but also ferromagnets and superconductors. Recently, the discovery of topological insulators has revealed a new paradigm that solid states respecting the same symmetries can be topologically distinct. The same idea relates a cup and a donut, yet distinguishes a sphere and a torus. Such a topological viewpoint has created a revolution in condensed matter science that has far ranging implications over coming decades. In this talk, I will introduce how the topological insulators arise from band inversion, and how they are protected by symmetries and enriched under symmetry breaking. I will then generalize these essential ideas to other experimentally feasible systems such as superconductors with Weyl and Majorana excitations. Fascinating and significant implications including experimental signatures and potential applications will be discussed.