Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 51: Topological Superconductors

TT 51.2: Talk

Thursday, March 20, 2025, 17:00–17:15, H32

Non-Hermitian Topology in Multi-Terminal Superconducting Junctions — •Valentin Wilhelm, David Christian Ohnmacht, Hannes Weisbrich, and Wolfgang Belzig — Universität Konstanz, Konstanz, Germany

Recent experimental advancements in dissipation control have yielded significant insights into nonhermitian Hamiltonians for open quantum systems. Of particular interest are the topological characteristics exhibited by these non-hermitian systems, that arise from exceptional points–distinct degeneracies unique to such systems. In this study, we focus on Andreev bound states in multiterminal Josephson junctions with non-hermiticity induced by normal metal or ferromagnetic leads [1]. By investigating several systems of different synthetic dimensions and symmetries, we predict fragile and stable non-hermitian topological phases in these engineered superconducting systems.

[1] D.C. Ohnmacht, V. Wilhelm, H. Weisbrich, W. Belzig,
arXiv:2408.01289 (2024).

Keywords: Superconductivity; Symmetries in condensed matter; Non-Hermitian systems; Andreev bound states; Topological phases of matter