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Overlap junctions for high coherence superconducting qubits



Xian Wu, Junling Long, Hsiang S. Ku, Russell Lake, Mustafa Bal, David P. Pappas


Fabrication of sub-micron Josephson junctions is demonstrated using standard processing techniques for high-coherence, superconducting qubits. These junctions are made in two separate lithography steps with normal-angle evaporation. Most significantly, this work demonstrates that it is possible to achieve high coherence with junctions formed on aluminum surfaces cleaned in situ with Ar milling before the junction oxidation. This method eliminates the angle-dependent shadow masks typically used for small junctions. Therefore, this is conducive to the implementation of typical methods for improving margins and yield using conventional CMOS processing. The current method uses electron-beam lithography and an additive process to define the top and bottom electrodes. Extension of this work to optical lithography and subtractive processes is discussed.
Applied Physics Letters


quantum, Josephson junction, fabrication, qubit, lithography, high coherence, oxidation, angle-dependent shadow masks, aluminum, Ar, electron-beam, optical, subtractive processes


Wu, X. , Long, J. , Ku, H. , Lake, R. , Bal, M. and Pappas, D. (2017), Overlap junctions for high coherence superconducting qubits, Applied Physics Letters, [online], (Accessed July 19, 2024)


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Created May 26, 2017, Updated June 26, 2020