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Topological fine structure of an energy band
Hui Liu, Cosma Fulga, Emil J. Bergholtz +1
A band with a nonzero Chern number cannot be fully localized by weak disorder. There must remain at least one extended state, which ``carries the Chern number.'' Here we show that…
Braids and Higher-order Exceptional Points from the Interplay Between Lossy Defects and Topological Boundary States
Zi-Jian Li, Gabriel Cardoso, Emil J. Bergholtz +1
We show that the perturbation of the Su-Schrieffer-Heeger chain by a localized lossy defect leads to higher-order exceptional points (HOEP). Depending on the location of the defect…
Non-Hermitian extended midgap states and bound states in the continuum
Maria Zelenayova, Emil J. Bergholtz
We investigate anomalous localization phenomena in non-Hermitian systems by solving a class of generalized Su-Schrieffer-Heeger/Rice-Mele models and by relating their provenance to…
Nodal phases in non-Hermitian wallpaper crystals
J. Lukas K. König, Felix Herber, Emil J. Bergholtz
Symmetry and non-Hermiticity play pivotal roles in photonic lattices. While symmetries such as parity-time () symmetry have attracted ample attention, more intricate…
Band mixing in the quantum anomalous Hall regime of twisted semiconductor bilayers
Ahmed Abouelkomsan, Aidan P. Reddy, Liang Fu +1
Remarkable recent experiments have observed fractional quantum anomalous Hall (FQAH) effects at zero field and unusually high temperatures in twisted semiconductor bilayer MoTe$…
Homotopy, Symmetry, and Non-Hermitian Band Topology
Kang Yang, Zhi Li, J. Lukas K. König +3
Non-Hermitian matrices are ubiquitous in the description of nature ranging from classical dissipative systems, including optical, electrical, and mechanical metamaterials, to scatt…