The effect of interactions on 2D fermionic symmetry-protected topological phases with Z2 symmetry

Understand

We study the effect of interactions on 2D fermionic symmetry-protected topological (SPT) phases using the recently proposed braiding statistics approach.

• We focus on a simple class of examples: superconductors with a Z2 Ising symmetry.
• Although these systems are classified by Z in the noninteracting limit, our results suggest that the classification collapses to Z8 in the presence of interactions -- consistent with previous work that analyzed the stability of the edge.
• Specifically, we show that there are at least 8 different types of Ising superconductors that cannot be adiabatically connected to one another, even in the presence of strong interactions.