paper

-breaking threshold in spatially asymmetric Aubry-Andre Harper models: hidden symmetry and topological states

arXiv:1504.03767 · doi:10.1103/PhysRevA.93.062101

Abstract

Aubry-Andre Harper (AAH) lattice models, characterized by reflection-asymmetric, sinusoidally varying nearest-neighbor tunneling profile, are well-known for their topological properties. We consider the fate of such models in the presence of balanced gain and loss potentials located at reflection-symmetric sites. We predict that these models have a finite breaking threshold only for {\it specific locations} of the gain-loss potential, and uncover a hidden symmetry that is instrumental to the finite threshold strength. We also show that the topological edge-states remain robust in the -symmetry broken phase. Our predictions substantially broaden the possible realizations of a -symmetric system.

8 pages, 5 figures

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