Seminars

Seminar Series on “Topological orders and category theory” （Spring, 2023）

In the spring of 2023, our seminar series on “Topological orders and category theory” will be hold on every Tuesday. The hours of the talks can be different according to the time zone of the speaker.

  • Feb. 28, 2023, no talk
  • Mar. 7, 2023, 7PM-9PM (Beijing), Lakshya Bhardwaj (Oxford University, UK)
  • Mar. 14, 2023, 7PM-9PM (Beijing), Apoorv Tiwari (KTH Royal Institute of Technology, Stockholm, Sweden)
  • Mar. 21, 2023, Zhihao Duan (KIAS, Korea)
  • Mar. 28, 2023, 9AM-11AM Kansei Inamura (University of Tokyo)
    1. Title: Fusion category symmetries of 1+1d bosonic and fermionic topological field theories
    2. Abstract: Generalized symmetries in two-dimensional spacetime are described by the algebraic structure of topological line defects. In particular, when the number of topological lines is finite, their algebraic structure is described by a fusion category or a superfusion category depending on whether the system is bosonic or fermionic. For this reason, finite generalized symmetries in 1+1 dimensions are called fusion category symmetries. In this talk, we will construct 1+1d bosonic and fermionic topological field theories (TQFTs) with fusion category symmetries using the state sum construction of TQFTs and the pullback of fusion category symmetries. These TQFTs can be realized by the ground states of commuting projector Hamiltonians on the lattice. We will also derive the fermionization formula of fusion category symmetries by comparing the symmetries of bosonic TQFTs with those of fermionic TQFTs. Examples include the fermionization of finite group symmetries and Kramers-Wannier-like self-dualities. This talk is based on arXiv:2110.12882 and 2206.13159.
  • Apr. 4, 2023, 9AM-11AM Nikita Sopenko (Caltech)
  • Apr. 11, 2023, 9AM-11AM Yu Leon Liu (Harvard)