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Coherent superconducting qubits from a subtractive junction fabrication process

Stehli, Alexander; Brehm, Jan David; Wolz, Tim; Baity, Paul; Danilin, Sergey; Seferai, Valentino; Rotzinger, Hannes; Ustinov, Alexey V.; Weides, Martin

Abstract:
Josephson tunnel junctions are the centerpiece of almost any superconducting electronic circuit, including qubits. Typically, the junctions for qubits are fabricated using shadow evaporation techniques to reduce dielectric loss contributions from the superconducting film interfaces. In recent years, however, sub-micron scale overlap junctions have started to attract attention. Compared to shadow mask techniques, neither an angle dependent deposition nor free-standing bridges or overlaps are needed, which are significant limitations for wafer-scale processing. This comes at the cost of breaking the vacuum during fabrication, but simplifies integration in multi-layered circuits, implementation of vastly different junction sizes, and enables fabrication on a larger scale in an industrially-standardized process. In this work, we demonstrate the feasibility of a subtractive process for fabrication of overlap junctions. In an array of test contacts, we find low aging of the average normal state resistance of only 1.6\% over 6 months. We evaluate the coherence properties of the junctions by employing them in superconducting transmon qubits. ... mehr



Zugehörige Institution(en) am KIT Institut für Quantenmaterialien und -technologien (IQMT)
Physikalisches Institut (PHI)
Publikationstyp Forschungsbericht/Preprint
Publikationsjahr 2020
Sprache Englisch
Identifikator KITopen-ID: 1000125629
Umfang 8 S.
Nachgewiesen in arXiv
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