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arXiv · 1904.10764

Exceptional rings protected by emergent symmetry for mechanical systems

Tsuneya Yoshida·Yasuhiro Hatsugai
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Abstract

We propose mechanical systems, described by Newton's equation of motion, as suited platforms for symmetry protection of non-Hermitian topological degeneracies. We point out that systems possess emergent symmetry, which is a unique properties of mechanical systems. Because of the emergent symmetry, in contrast to other systems, fine-tuning of parameters (e.g., gain and loss) is not required to preserve the symmetry protecting exceptional rings in two dimensions. The presence of symmetry-protected exceptional rings (SPERs) in two dimensions is numerically demonstrated for a mechanical graphene with friction. Furthermore, classification of symmetry-protected non-Hermitian degeneracies is addressed by taking into account the above special characteristics of mechanical systems.

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Tsuneya Yoshida, Yasuhiro Hatsugai. 2019-04-24. Exceptional rings protected by emergent symmetry for mechanical systems. https://doi.org/10.1103/physrevb.100.054109

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