1. Mitigation of interfacial dielectric loss in aluminum-on-silicon superconducting qubits.
- Author
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Biznárová, Janka, Osman, Amr, Rehnman, Emil, Chayanun, Lert, Križan, Christian, Malmberg, Per, Rommel, Marcus, Warren, Christopher, Delsing, Per, Yurgens, August, Bylander, Jonas, and Fadavi Roudsari, Anita
- 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 - Abstract
We demonstrate aluminum-on-silicon planar transmon qubits with time-averaged T
1 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. [ABSTRACT FROM AUTHOR]- Published
- 2024
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