SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 54: Quantum Coherence and Quantum Information Systems II
TT 54.1: Vortrag
Donnerstag, 30. März 2023, 15:00–15:15, HSZ 304
Dominant materials losses in superconducting circuits based on tantalum thin films — •Ritika Dhundhwal1, Haoran Duan2, Dirk Fuchs1, Alexander Welle3, Mahya Khorramshahi1, Jasmin Aghassi-Hagmann2, Ioan M. Pop1, and Thomas Reisinger1 — 1Institut für Quantenmaterialien und technologien — 2Institut für Nanotechnologie — 3Institut für Funktionelle Grenzflächen, Karlsruher Institut für Technologie
Superconducting quantum circuits are a promising hardware platform in the fields of quantum computing and detection. To improve their performance, exploring new materials is highly relevant. One promising candidate material is tantalum (Ta), which was recently shown to improve transmon qubit lifetimes[1]. However, the understanding of the dominant loss mechanisms related to Ta is limited. Here, we present a study of losses in epitaxial Ta films deposited using magnetron sputtering, with the aim of relating basic material properties to 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, Time-of-Flight secondary-ion mass spectrometry, scanning electron microscopy and superconducting transition temperature measurements. We fabricated lumped element resonators from the films and measured their quality factors as a function of photon number and temperature. In addition, we vary the energy participation ratio of Ta metal-substrate interface to find the dominant loss mechanism.
[1] A. P. M. Place et al., Nat. Commun. 12, 1779 (2021)