Topological states in a non-Hermitian two-dimensional Su-Schrieffer-Heeger model

Yüce, C.; Ramezani, Hamidreza

doi:10.1103/physreva.100.032102

Cited by 82 publications

(36 citation statements)

References 63 publications

(56 reference statements)

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“…A similar type of IS breaking has been employed in previous studies of non-Hermitian systems [34,39,[62][63][64][65][66], typically in the form of neighboring regions or strips of gain and loss. We want to emphasize that in our approach gain and loss are dispersed over the lattice, such that each unit cell contains both.…”

Section: The Modelmentioning

confidence: 99%

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Topological protection in non-Hermitian Haldane honeycomb lattices

Reséndiz-Vázquez

Tschernig

Pérez-Leija

et al. 2020

Phys. Rev. Research

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Topological phenomena in non-Hermitian systems have recently become a subject of great interest in the photonics and condensed-matter communities. In particular, the possibility of observing topologically protected edge states in non-Hermitian lattices has sparked an intensive search for systems where this kind of states are sustained. Here we present a study of the emergence of topological edge states in two-dimensional Haldane lattices exhibiting balanced gain and loss. In line with recent studies on other Chern insulator models, we show that edge states can be observed in the so-called broken PT-symmetric phase, that is, when the spectrum of the gain-loss-balanced system's Hamiltonian is not entirely real. More importantly, we find that such topologically protected edge states emerge irrespective of the lattice boundaries, namely, zigzag, bearded, or armchair.

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Section: The Modelmentioning

confidence: 99%

“…We want to emphasize that in our approach gain and loss are dispersed over the lattice, such that each unit cell contains both. Yuce et al [66] investigated such an interspersed gainloss distribution in the context of the two-dimensional Su-Schrieffer-Heeger model, but no real-valued edge states were found.…”

Section: The Modelmentioning

confidence: 99%

Topological protection in non-Hermitian Haldane honeycomb lattices

Reséndiz-Vázquez

Tschernig

Pérez-Leija

et al. 2020

Phys. Rev. Research

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“…Non‐Hermitian, another significant approach to tackle with the issues of topological physics besides Hermitian, abounds with wonderful examples of the fruitful interplay between condensed matter physics and quantum optomechanics. [ 1–4 ] The main reason that tremendous research progress made in non‐Hermitian system [ 5–7 ] in recent years primarily originates in that the Hermitian system is deprived of its superiority and is insufficient to characterize the systems with asymmetric coupling. In general, the studies of non‐Hermitian Hamiltonian initially date back to the early days of Hermitian system with parity‐time (

P T

) symmetry.…”

Section: Introductionmentioning

confidence: 99%

Topological Phase Transition and Eigenstates Localization in a Generalized Non‐Hermitian Su–Schrieffer–Heeger Model

Zhang

Huang

et al. 2020

Annalen der Physik

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The topological properties of a generalized non‐Hermitian Su–Schrieffer–Heeger model are investigated and it is demonstrated that the non‐Hermitian phase transition and the non‐Hermitian skin effect can be induced by intra‐cell asymmetric coupling under open boundary conditions. Through investigating and calculating the non‐Hermitian winding number with generalized Brillouin zone theory, it is found that the present non‐Hermitian system has an exact bulk‐boundary correspondence relationship. Meanwhile, the non‐Hermitian winding number is used to characterize the non‐Hermitian phase transition and determine the phase transition boundary, and it is found that the non‐Hermitian phase transition is not completely induced by the asymmetric coupling strength. By means of the mean inverse participation ratio, the factors that affect the eigenstates localization are shown and it is revealed that large system size or large asymmetric coupling strength can leave the system in the localized state. Additionally, it is found that for the asymmetric coupling strength and the system size, the eigenstates localization is much more sensitive to the asymmetric coupling strength.

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“…Different from adding gain and loss to the two sublattices of a standard SSH chain [18,19], here one unit cell consists of four sites instead of two, and the non-Hermiticity opens a band gap rather than narrows down the band gap. The nontrivial topology is captured by a biorthogonal polarization [15,32,34,44]…”

mentioning

confidence: 99%