Regensburg 2022 – scientific programme

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QI: Fachverband Quanteninformation

QI 13: Implementations: Superconducting Qubits

QI 13.10: Talk

Friday, September 9, 2022, 12:15–12:30, H8

Towards cQED experiments with in-situ fabrication of topological insulator Josephson junctions — •Lucas Janssen, Jonas Krause, Christian Dickel, Alexey Taskin, Roozbeh Yazdampanah Ravari, Anjana Uday, Gertjan Lippertz, and Yoichi Ando — AG Ando, PH2, Universität zu Köln, Germany

Circuit quantum electrodynamics experiments with topological insulator (TI) Josephson junctions (JJs) are a promising path towards finding and studying Majorana zero modes. However, the fabrication of TI JJs is challenging. For our topological insulator, we use MBE grown ternary TI (BiSb)_2Te_3. The interface between the proximitising superconductor and the TI film is critically important for the quality of the JJ, which in turn is vital for microwave performance. Hence, we have been fabricating TI JJs with in-situ deposited niobium. However, etching the niobium to define a JJ has proven challenging. We are exploring a combination of titanium and aluminium as an alternative superconductor. An alternative to this etching step is stencil mask technology. We will present our progress in JJ fabrication and possibly first cQED measurements.