{
    "abstract": "The lifetime of superconducting qubits is limited by dielectric loss, and a major source of dielectric loss is the native oxide present at the surface of the superconducting metal. Specifically, tantalum-based superconducting qubits have been demonstrated with record lifetimes, but a major source of loss is the presence of two-level systems in the surface tantalum oxide. Here, we demonstrate a strategy for avoiding oxide formation by encapsulating the tantalum with noble metals that do not form native oxide. By depositing a few nanometers of Au or AuPd alloy before breaking vacuum, we completely suppress tantalum oxide formation. Microwave loss measurements of superconducting resonators reveal that the noble metal is proximitized, with a superconducting gap over 80% of the bare tantalum at thicknesses where the oxide is fully suppressed. Our findings suggest that losses in resonators fabricated by subtractive etching are dominated by oxides on the sidewalls, pointing to total surface encapsulation by additive fabrication as a promising strategy for eliminating surface oxide two-level system loss in superconducting qubits.",
    "authors": [
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Ray D",
            "initials": "RD",
            "lastname": "Chang"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Nana",
            "initials": "N",
            "lastname": "Shumiya"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Russell A",
            "initials": "RA",
            "lastname": "McLellan"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Yifan",
            "initials": "Y",
            "lastname": "Zhang"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Matthew P",
            "initials": "MP",
            "lastname": "Bland"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Faranak",
            "initials": "F",
            "lastname": "Bahrami"
        },
        {
            "affiliation": "Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.\nBrookhaven National Laboratory, Condensed Matter Physics and Materials Science Department, Upton, New York 11973, USA.",
            "firstname": "Junsik",
            "initials": "J",
            "lastname": "Mun"
        },
        {
            "affiliation": "Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.",
            "firstname": "Chenyu",
            "initials": "C",
            "lastname": "Zhou"
        },
        {
            "affiliation": "Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.",
            "firstname": "Kim",
            "initials": "K",
            "lastname": "Kisslinger"
        },
        {
            "affiliation": "Princeton University, Princeton Materials Institute, Princeton, New Jersey 08540, USA.",
            "firstname": "Guangming",
            "initials": "G",
            "lastname": "Cheng"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Basil M",
            "initials": "BM",
            "lastname": "Smitham"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Alexander C",
            "initials": "AC",
            "lastname": "Pakpour-Tabrizi"
        },
        {
            "affiliation": "Princeton University, Princeton Materials Institute, Princeton, New Jersey 08540, USA.",
            "firstname": "Nan",
            "initials": "N",
            "lastname": "Yao"
        },
        {
            "affiliation": "Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Department, Upton, New York 11973, USA.",
            "firstname": "Yimei",
            "initials": "Y",
            "lastname": "Zhu"
        },
        {
            "affiliation": "Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.",
            "firstname": "Mingzhao",
            "initials": "M",
            "lastname": "Liu"
        },
        {
            "affiliation": "Princeton University, Department of Chemistry, Princeton, New Jersey 08540, USA.",
            "firstname": "Robert J",
            "initials": "RJ",
            "lastname": "Cava"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Sarang",
            "initials": "S",
            "lastname": "Gopalakrishnan"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Andrew A",
            "initials": "AA",
            "lastname": "Houck"
        },
        {
            "affiliation": "Princeton University, Department of Electrical and Computer Engineering, Princeton, New Jersey 08540, USA.",
            "firstname": "Nathalie P",
            "initials": "NP",
            "lastname": "de Leon"
        }
    ],
    "conclusions": null,
    "copyrights": null,
    "doi": "10.1103/PhysRevLett.134.097001",
    "journal": "Physical review letters",
    "keywords": [],
    "methods": null,
    "publication_date": "2025-03-25",
    "pubmed_id": "40131031",
    "results": null,
    "title": "Eliminating Surface Oxides of Superconducting Circuits with Noble Metal Encapsulation.",
    "xml": "<Element 'PubmedArticle' at 0x7885050816c0>"
}