Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 32: Focus Session: Topological Devices (joint session TT/KFM)

TT 32.7: Talk

Thursday, September 8, 2022, 18:00–18:15, H10

First magnetic field measurements of a topological insulator based Transmon Qubit — •Anne Schmidt¹, Tobias W. Schmitt¹, Chenlu Liu², Albert Hertel¹, Christian Dickel³, Michael Schleenvoigt¹, Malcolm R. Connolly^2,4, Yoichi Ando³, Detlev Grützmacher¹, and Peter Schüffelgen¹ — ¹Peter Grünberg Institute & Jülich-Aachen Research Alliance, Forschungszentrum Jülich — ²Blackett Laboratory, Imperial College London — ³Institute of Physics II, University of Cologne — ⁴London Centre for Nanotechnology, University College London

Hybrid topological insulator (TI) – superconductor (S) heterostructures are a promising platform for the realization of topologically protected quantum computation based on Majorana zero modes. This promises fewer physical qubits for creating a logical qubit compared to conventional superconducting qubits. Our full in situ device fabrication, which combines selective area growth of thin (Bi,Sb)2Te3 films and stencil deposition of superconductive Nb has already shown to create highly transparent S-TI interfaces. Recently, we have demonstrated that this fabrication process can readily be integrated into cQED structures as building block for a transmon qubit and performed coherence measurements at zero magnetic field. Here, we will expand these measurements to finite magnetic fields, as in-plane magnetic fields are a requirement for restoring the topological phase in confined (Bi,Sb)2Te3 nanostructures. We present initial results on the magnetic field dependence of the T1 lifetime and the qubit’s anharmonicity.