Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 74: Topological Insulators

TT 74.2: Talk

Thursday, March 12, 2026, 09:45–10:00, CHE/0091

Characterization of TI nanowire junctions using resonator circuits — •Lucas Marten Janssen, Jorge Esteban Bolio, Christian Dickel, and Yoichi Ando — Physics Institute II, University of Cologne, Zülpicher Str. 77, 50937 Köln, Germany

Topological insulators (TIs) are being investigated for their potential to host Majorana Zero Modes (MZMs). Specifically, TI nanowires proximitized by a conventional superconductor have shown signatures of potential topological phase transitions [1]. Microwave measurements can be used to investigate the hardness of the gap [2] and to reconstruct the current-phase relationship [3]. Additionally, high-frequency operation could be necessary to eventually realize topological qubits. To assess the quality of our TI nanowire junctions, we design co-planar waveguide resonator circuits of NbTiN with a parallel plate capacitor to ground on one side and a connection to ground through the nanowire junction on the other side. This allows us to measure the sub-gap resistance and the current-phase relationship of the junction. In order to investigate the TI nanowire in the topological regime, an in-plane magnetic field of about 1 T needs to be applied. The resonators are engineered to be compatible with such fields.
[1] Nikodem et al., arXiv:2412.07993 (2024)
[2] Schmidt et al., Nat. Commun. 9, 4069 (2018)
[3] Uhl et al., Phys. Rev. Applied 22, 064052 (2024)

Keywords: Topological insulators; High frequency measurement; Superconductivity