Berlin 2024 – wissenschaftliches Programm
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QI: Fachverband Quanteninformation
QI 18: Poster II
QI 18.31: Poster
Mittwoch, 20. März 2024, 11:00–14:30, Poster A
Optimization of Niobium Film Stress for Superconducting Quantum Circuits — •David Bunch1,2, Leon Koch1,2, Niklas Bruckmoser1,2, Lasse Södergren1,2, and Stefan Filipp1,2 — 1Walther Meißner Institut, Bayerische Akademie der Wissenschaften, Garching, Germany — 2Technical University of Munich, TUM School of Natural Sciences, Physics Department, Garching, Germany
High quality superconducting films are important for high coherence superconducting quantum processors. Past studies have shown that intrinsic stress effects the superconducting critical temperature and amount of bulk oxidation of sputtered thin films. Two level systems hosted in film oxides are a major contributor to losses in superconducting circuits, so film stress should controlled during sputtering via the argon gas pressure. In this work, we sputter niobium thin films with a wide range of stresses, from compressive to tensile. We evaluate the films' suitability for quantum circuits by performing thin film measurements such as critical temperature and residual resistivity ratio measurements. Eventually we test the quality of the thin films by measuring the internal quality factor of coplanar waveguide resonators as a function of photon number.
Keywords: Superconductors; Resonators; Films; Stress