Full commuting projector Hamiltonians of interacting symmetry-protected topological phases of fermions

Journal Article · 01 October 2018 · Physical Review. B

DOI: https://doi.org/10.1103/physrevb.98.165104 · OSTI ID:1571111

Tantivasadakarn, Nathanan ^[1]; Vishwanath, Ashvin ^[1]

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1. Harvard Univ., Cambridge, MA (United States)

In this work, using the decorated domain wall procedure, we construct finite-depth local unitaries that realize fermionic symmetry-protected topological (SPT) phases. This results in explicit full commuting projector Hamiltonians, where "full" implies the fact that the ground state as well as all excited states of these Hamiltonians realize the nontrivial SPT phase. We begin by constructing explicit examples of 1+1D phases protected by the symmetry group G=$$\mathbb{Z}_2^T$$×$$\mathbb{Z}_2^F$$, which also has a free fermion realization in class BDI, and by the symmetry group G=$$\mathbb{Z}_4$$×$$\mathbb{Z}_4^F$$, which does not. We then turn to 2+1D, and construct the square roots of the Levin-Gu bosonic SPT phase, protected by $$\mathbb{Z}_2$$×$$\mathbb{Z}_2^F$$ symmetry, in a concrete model of fermions and spins on the triangular lattice. Edge states and the anomalous symmetry action on them are explicitly derived. Although this phase has a free fermion representation as two copies of p+ip superconductors combined with their p-ip counterparts with a different symmetry charge, the full set of commuting projectors is only realized in the strongly interacting version, which also implies that it admits a many-body localized realization.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1571111
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 16 Vol. 98; ISSN 2469-9950; ISSN PRBMDO
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English