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On the classification of (2+1)D topological order via modular fusion categories

Mathematical Physics Seminar

Speaker: Colleen Delaney, UC Berkeley
Location: 3204 QMAP
Start time: Mon, Oct 23 2023, 3:10PM

Typically two 2d quantum systems exhibiting distinct topological order can be distinguished from each other simply by comparing the behavior of the ground states on a torus under modular transformations (S and T matrices). However, there are examples which can not be distinguished in this manner and in practice require one to understand the more fine-grained characterization of topological order via modular fusion categories. Such ``modular isotopes" can even occur in generally well-understood theories, namely twisted quantum double models. I will give an accessible review of modular fusion category theory from both the points of view of a physicist and a mathematician, and then argue that both are helpful for fully appreciating the distinction between these examples of topological order.