1. Enhanced Superconducting Qubit Performance Through Ammonium Fluoride Etch
- Author
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Kopas, Cameron J., Goronzy, Dominic P., Pham, Thang, Castanedo, Carlos G. Torres, Cheng, Matthew, Cochrane, Rory, Nast, Patrick, Lachman, Ella, Zhelev, Nikolay Z., Vallieres, Andre, 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., and Yadavalli, Kameshwar
- Subjects
Condensed Matter - Materials Science ,Quantum Physics - Abstract
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 $\text{T}_1$ by $\sim22\%$ ($p=0.002$), 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 prior to niobium deposition also show $\sim33\%$ 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.
- Published
- 2024
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