Relation between insulating QRSPTs and Green’s function zeros

Establish whether insulating quantum restored symmetry protected topological (QRSPT) phases are characterized by topological zeros in the single-particle fermionic Green’s function, and specify the conditions under which such Green’s function zeros arise within the QRSPT paradigm.

Background

The paper introduces quantum restored symmetry protected topological (QRSPT) phases, where a symmetry broken at the mean-field level is restored by quantum fluctuations, leading to reemergent topological features. For their one-dimensional example—a spinful Su–Schrieffer–Heeger chain coupled to fluctuating s-wave superconducting islands—the authors map out a phase diagram with a QRSPT phase and confirm its characteristics analytically and numerically.

They note a broader expectation in the literature that insulating interacting topological phases can be associated with topological zeros of the fermionic Green’s function, but emphasize that for QRSPTs this relationship has not been established. Clarifying whether insulating QRSPTs are indeed captured by Green’s function zeros would link QRSPTs to established many-body topological diagnostics.