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Full Commuting Projector Hamiltonians of Interacting Symmetry-Protected Topological Phases of Fermions

Speaker:Mr. Nathanan Tantivasadakarn
Affiliation:Harvard University
Date:July 8, 2019 (Monday)
Time:4:00 p.m.
Venue:Room 522, 5/F, Chong Yuet Ming Physics Building, HKU


Topological insulators & superconductors are well known examples of SPT phases, which at zero temperature cannot be connected to a atomic insulator without closing the gap or breaking the symmetry. In this work, we study fermionic SPT phases from a strongly-interacting point of view by focusing on models in which the Hamiltonian can be written as a full set of commuting projectors. This allows us to extend the notion of topology beyond the ground state, which can be applied to non-equilibrium systems e.g. with many-body localization. Specifically, we study a theory whose free fermion representation consists of two copies of p + ip superconductors combined with their p − ip counterparts with different symmetry charges. Although symmetric local Wannier functions are not allowed for this free theory, we construct a strongly interacting full commuting projector Hamiltonian which realizes this phase. We also construct SPT phases that have no free fermion analog.
(Based on arXiv:1806.09709 with Ashvin Vishwanath)

Coffee and tea will be served 20 minutes prior to the seminar.

Anyone interested is welcome to attend.