Quantum Theory Seminar with Julian May-Mann (University of Illinois Urbana-Champaign)

Field Theories of Higher-Order Topological Insulators in Two-Dimensions

https://arxiv.org/abs/2108.00008

Two-dimensional higher-order topological insulators can display a number of exotic phenomena, such as half-integer charges localized at corners or disclination defects. In this talk, I will analyze these phenomena, focusing on the paradigmatic example of the quadrupole insulator (Benalcazar-Bernevig-Hughes model) with 

C4 rotation symmetry, and present a topological field theory description of the mixed geometry-charge responses. This theory provides a unified description of the corner and disclination charges in terms of a physical geometry (which encodes disclinations), and an effective geometry (which encodes corners). I will also extend this analysis to interacting systems, and predict the response of a fractional quadrupole insulator with topological order.

Zoom link for the seminar is 
https://cornell.zoom.us/j/96116630382?pwd=WkhDQjVRaTBTaXBxVk0ya0FnZjNLQT09

For all local attendance, the venue is Clark 701.