Asia Pacific Physics Week 2024 (APPW2024)

Tuesday, Nov. 5, 2024 

2:00 PM - 2:40 PM  Plenary Talk: Masaki Oshikawa (University of Tokyo)

Wandering around Symmetry-Protected Topological Phases with duality

Masaki Oshikawa

Institute for Solid State Physics and Kavli Institute for Physics and Mathematics of Universe, University of Tokyo, Kashiwa 277-8581 Japan

Symmetry-Protected Topological (SPT) phases are, as the name suggests, topological　phases without any conventional local order parameter, but distinct from the trivial phase only in the presence of a certain symmetry. The concept was first proposed by Gu and Wen in 2009 as a generalization of topological insulators discovered earlier, However, the prototypical example of the SPT phases, the Haldane gap phase in odd-integer spin chains, was discovered much earlier in 1980s and its numerous “topological” properties were uncovered by 1990s. In particular, a non-local transformation introduced by Kennedy and Tasaki maps the Haldane gap phase and a conventional Spontaneous Symmetry Breaking (SSB) phase. The Kennedy-Tasaki duality could have naturally led to the concept of the SPT phases.

In this talk, I will review the concept of SPT phases from the duality point of view, and its historical developments. I will also discuss the recent resurgence of the duality approach, with applications including a systematic construction of SPT phases including a novel variety of “gapless SPT phases”.