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TT: Fachverband Tiefe Temperaturen
TT 57: Topology: Poster
TT 57.21: Poster
Mittwoch, 20. März 2024, 15:00–18:00, Poster E
Symmetry-enforced topological band degeneracies in non-Hermitian periodic systems — •Reuel Dsouza1,2 and Andreas Schnyder1 — 1Max-Planck-Institute for Solid State Physics, D-70569 Stuttgart, Germany — 2Department of Physics, University of Stuttgart, Germany
Non-Hermitian Hamiltonians are effective descriptions of non-equilibrium systems, in which quantities such as energy or particle number are not conserved. Similar to Hermitian systems, periodic non-Hermitian Hamiltonians can exhibit non-trivial band topologies, depending on the on-site and lattice symmetries. An important class of symmetries that gives rise to topological band degeneracies are the non-symmorphic symmetries, such as screw rotation or glide mirror. Here, we apply these symmetries to non-Hermitian Bloch Hamiltonians. We show that these symmetries give rise to interesting complex energy eigenvalue spectra with symmetry-enforced exceptional points as well as regular band degeneracies. We characterize these degeneracies with discriminant and vorticity numbers and develop a general classification of symmetry-enforced band degeneracies.
Keywords: non-hermitian; open quantum systems; band topology; symmetry enforced; band degeneracies