Boundary Supersymmetry of (1+1)D Fermionic Symmetry-Protected Topological Phases

We prove that the boundaries of all nontrivial (1 + 1)-dimensional intrinsically fermionic symmetryprotected-topological phases, protected by finite on-site symmetries (unitary or antiunitary), are supersymmetric quantum mechanical systems. This supersymmetry does not require any fine-tuning of the underlying Hamiltonian, arises entirely as a consequence of the boundary 't Hooft anomaly that classifies the phase, and is related to a Bose-Fermi degeneracy different in nature from other well known degeneracies such as Kramers doublets.

Automated summary

It has been proven that the boundaries of all nontrivial (1 + 1)-dimensional intrinsically fermionic symmetry-protected-topological phases, protected by finite on-site symmetries (unitary or antiunitary), are supersymmetric quantum mechanical systems. This supersymmetry arises as a consequence of the boundary 't Hooft anomaly that classifies the phase, and is distinct from other well-known degeneracies such as Kramers doublets.