Enhanced superconducting qubit performance through ammonium fluoride etch

The performance of superconducting qubits is often limited by dissipation and two-level systems (TLS) losses. The dominant sources of these losses are believed to originate from amorphous materials and defects at interfaces and surfaces, likely as a result of fabrication processes or ambient exposur...

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Veröffentlicht in:Materials for quantum technology 2024-12, Vol.4 (4), p.45101
Hauptverfasser: Kopas, Cameron J, Goronzy, Dominic P, Pham, Thang, Torres Castanedo, Carlos G, Cheng, Matthew, Cochrane, Rory, Nast, Patrick, Lachman, Ella, Zhelev, Nikolay Z, Vallières, André, Murthy, Akshay A, Oh, Jin-su, Zhou, Lin, Kramer, Matthew J, Cansizoglu, Hilal, Bedzyk, Michael J, Dravid, Vinayak P, Romanenko, Alexander, Grassellino, Anna, Mutus, Josh Y, Hersam, Mark C, Yadavalli, Kameshwar
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Sprache:eng
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Zusammenfassung:The performance of superconducting qubits is often limited by dissipation and two-level systems (TLS) losses. The dominant sources of these losses are believed to originate from amorphous materials and defects at interfaces and surfaces, likely as a result of fabrication processes or ambient exposure. Here, we explore a novel wet chemical surface treatment at the Josephson junction-substrate and the substrate-air interfaces by replacing a buffered oxide etch (BOE) cleaning process with one that uses hydrofluoric acid followed by aqueous ammonium fluoride. We show that the ammonium fluoride etch process results in a statistically significant improvement in median T 1 by ∼ 22 % ( p = 0.002), and a reduction in the number of strongly-coupled TLS in the tunable frequency range. Microwave resonator measurements on samples treated with the ammonium fluoride etch after niobium deposition and etching also show ∼ 33 % lower TLS-induced loss tangent compared to the BOE treated samples. As the chemical treatment primarily modifies the Josephson junction-substrate interface and substrate-air interface, we perform targeted chemical and structural characterizations to examine materials differences at these interfaces and identify multiple microscopic changes that could contribute to decreased TLS losses.
ISSN:2633-4356
2633-4356
DOI:10.1088/2633-4356/ad88cc