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arXiv · 1504.03767

$\mathcal{PT}$-breaking threshold in spatially asymmetric Aubry-Andre Harper models: hidden symmetry and topological states

Andrew K. Harter·Tony E. Lee·Yogesh N. Joglekar
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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 $\pm i\gamma$ located at reflection-symmetric sites. We predict that these models have a finite $\mathcal{PT}$ 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 $\mathcal{PT}$-symmetry broken phase. Our predictions substantially broaden the possible realizations of a $\mathcal{PT}$-symmetric system.

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Andrew K. Harter, Tony E. Lee, Yogesh N. Joglekar. 2015-04-15. $\mathcal{PT}$-breaking threshold in spatially asymmetric Aubry-Andre Harper models: hidden symmetry and topological states. https://doi.org/10.1103/physreva.93.062101

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