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- Title
Mitigation of interfacial dielectric loss in aluminum-on-silicon superconducting qubits.
- Authors
Biznárová, Janka; Osman, Amr; Rehnman, Emil; Chayanun, Lert; Križan, Christian; Malmberg, Per; Rommel, Marcus; Warren, Christopher; Delsing, Per; Yurgens, August; Bylander, Jonas; Fadavi Roudsari, Anita
- Abstract
We demonstrate aluminum-on-silicon planar transmon qubits with time-averaged T1 energy relaxation times of up to 270 μs, corresponding to Q = 5 million, and a highest observed value of 501 μs. Through materials analysis techniques and numerical simulations we investigate the dominant source of energy loss, and devise and demonstrate a strategy toward its mitigation. Growing aluminum films thicker than 300 nm reduces the presence of oxide, a known host of defects, near the substrate-metal interface, as confirmed by time-of-flight secondary ion mass spectrometry. A loss analysis of coplanar waveguide resonators shows that this results in a reduction of dielectric loss due to two-level system defects. The correlation between the enhanced performance of our devices and the film thickness is due to the aluminum growth in columnar structures of parallel grain boundaries: transmission electron microscopy shows larger grains in the thicker film, and consequently fewer grain boundaries containing oxide near the substrate-metal interface.
- Subjects
DIELECTRIC loss; QUBITS; SECONDARY ion mass spectrometry; THICK films; SUPERCONDUCTING quantum interference devices; COLUMNAR structure (Metallurgy); DIELECTRIC waveguides; ALUMINUM films; ELECTRON energy loss spectroscopy
- Publication
NPJ Quantum Information, 2024, Vol 10, Issue 1, p1
- ISSN
2056-6387
- Publication type
Article
- DOI
10.1038/s41534-024-00868-z