title: Topological zero-energy modes in gapless commensurate Aubry-André-Harper models.
abstract: The Aubry-André or Harper (AAH) model has been the subject of extensive theoretical research in the context of quantum localization. Recently, it was shown that one-dimensional quasicrystals described by the incommensurate AAH model has a nontrivial topology. In this Letter, we show that the commensurate off-diagonal AAH model is topologically nontrivial in the gapless regime and supports zero-energy edge modes. Unlike the incommensurate case, the nontrivial topology in the off-diagonal AAH model is attributed to the topological properties of the one-dimensional Majorana chain. We discuss the feasibility of experimental observability of our predicted topological phase in the commensurate AAH model.
authors.affiliation: Department of Physics, Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Sriram
authors.initials: S
authors.lastname: Ganeshan
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.forename: S
authors.initials: S
authors.lastname: Das Sarma