Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 31: Superconducting Electronics and Cryogenics: Poster Session
TT 31.15: Poster
Donnerstag, 8. September 2022, 15:00–18:00, P1
Materials losses in superconducting circuits based on tantalum thin films — •Ritika Dhundhwal1, Thomas Reisinger1, Haoran Duan2, Dirk Fuchs1, Matthieu Le Tacon1, Jasmin Aghassi-Hagmann2, and Ioan M. Pop1 — 1Institut für Quantenmaterialien und technologien (IQMT), Karlsruher Institut für Technologie (KIT) — 2Institut für Nanotechnologie (INT), Karlsruher Institut für Technologie (KIT)
Superconducting quantum circuits have very promising applications in the fields of quantum computing and detection. In general, their performance is limited by a variety of dissipation and noise sources. For mitigating these, the focus has been on improving microwave design and better fabrication processes. Another approach, recently in the spotlight, is to explore new materials entirely. One promising candidate superconducting material is Tantalum (Ta), which recently enabled record-breaking Transmon qubit lifetimes. However, there is a lack of conclusive evidence of the dominant loss mechanisms related to Ta. Here, we present a study of losses in epitaxial Ta films deposited using magnetron sputtering, with the aim of relating basic material properties and loss mechanisms. A variation in the deposition parameters (mainly substrate temperature) leads to structurally different films. We characterized these using high-resolution X-ray diffraction, scanning electron microscopy and measurements of the superconducting transition temperature. In addition, we fabricated lumped element resonators from the films using e-beam lithography and measured their quality factors as a function of photon number and temperature.