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Digital Circuits Using Self-Shunted Nb/NbxSi1-x/Nb Josephson Junctions



David I. Olaya, Paul Dresselhaus, Samuel Benz, Anna Herr, Quentin Herr, alex Ioannidis, Donald Miller, Alan Kleinsasser


For the first time superconducting digital circuits based on novel Josephson junctions with amorphous niobium-silicon (a-NbSi) barriers were designed, fabricated and tested. Compared with the resistively shunted aluminum-oxide-barrier junctions that are typically used for such circuits, the self-shunted nature of a-NbSi junctions enabled a two-fold increase in circuit density, while the relatively thick 10 nm barriers could potentially increase the circuit yield. Measurements were performed on a single-ux-quantum shift register and a static digital divider. The shift register operated with +-30 % bias margins, con rming reproducibility and uniformity of the junctions. The divider operated up to 165 GHz for a single value of bias current, which was only marginally less than that of a similar circuit fabricated with externally shunted AlOx tunnel-barrier junctions having a comparable 4.5 kA/cm2 critical current density.
Applied Physics Letters


Josephson devices, Josephson logic, Niobium, Superconducting devices, Superconducting device fabrication


Olaya, D. , Dresselhaus, P. , Benz, S. , Herr, A. , Herr, Q. , Ioannidis, A. , Miller, D. and Kleinsasser, A. (2010), Digital Circuits Using Self-Shunted Nb/NbxSi1-x/Nb Josephson Junctions, Applied Physics Letters, [online], (Accessed May 20, 2024)


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Created May 26, 2010, Updated October 12, 2021