Authors:

Owen Wood

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About Paper:

Superconducting quantum bits (qubits) are a leading platform for quantum computing. One of the main drawbacks is the relatively short coherence time, typically ~ 100 ms, for qubits that utilize superconducting Nb thin film capacitor pads. This is attributable to the RF lossy Nb oxide layer that has oxygen vacancies that lead to local magnetic moments. Here we examine a NbRe alloy (Nb0.18Re0.82) that has a superconducting TC ~ 7K-9K, close to that of Nb, but is mostly Re metal that has a minimal surface oxide. X-ray photoemission spectroscopy (XPS) is used to examine the surface oxide of the alloy thin films grown by sputtering. As-made amorphous films are compared with more ordered annealed films [1]. Focus here is on annealed films. The principal result is that the observed Nb oxide peaks are those of fully oxidized Nb2O5 in the annealed films, without evidence of oxygen vacancies. The alloy thus has promise as a replacement for Nb.

Source:

Illinois Institute of Technology

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Co-authors:

Owen Wood