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Title: Flat bands in lattices with non-Hermitian coupling
Authors: Leykam, Daniel
Flach, Sergej
Chong, Yi Dong
Keywords: Photonics
Quantum Interference Effects
Issue Date: 2017
Source: Leykam, D., Flach, S., & Chong, Y. D. (2017). Flat bands in lattices with non-Hermitian coupling. Physical Review B, 96(6), 064305-. doi:10.1103/PhysRevB.96.064305
Series/Report no.: Physical Review B
Abstract: We study non-Hermitian photonic lattices that exhibit competition between conservative and non-Hermitian (gain/loss) couplings. A bipartite sublattice symmetry enforces the existence of non-Hermitian flat bands, which are typically embedded in an auxiliary dispersive band and give rise to nondiffracting “compact localized states”. Band crossings take the form of non-Hermitian degeneracies known as exceptional points. Excitations of the lattice can produce either diffracting or amplifying behaviors. If the non-Hermitian coupling is fine-tuned to generate an effective π flux, the lattice spectrum becomes completely flat, a non-Hermitian analog of Aharonov-Bohm caging in which the magnetic field is replaced by balanced gain and loss. When the effective flux is zero, the non-Hermitian band crossing points give rise to asymmetric diffraction and anomalous linear amplification.
ISSN: 2469-9950
DOI: 10.1103/PhysRevB.96.064305
Rights: © 2017 American Physical Society (APS). This paper was published in Physical Review B and is made available as an electronic reprint (preprint) with permission of American Physical Society (APS). The published version is available at: []. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SPMS Journal Articles

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