In-situ bandaged Josephson junctions for superconducting quantum processors

In-situ bandaged Josephson junctions for superconducting quantum processors

Bilmes, Alexander (Karlsruhe Institut für Technologie)
Händel, Alexander K. (Karlsruhe Institut für Technologie)
Volosheniuk, S. (TU Delft QN/van der Zant Lab; Kavli institute of nanoscience Delft)
Ustinov, Alexey V. (Karlsruhe Institut für Technologie; National University of Science and Technology MISiS; Russian Quantum Center, Moscow)
Lisenfeld, Jürgen (Karlsruhe Institut für Technologie)

2021

Shadow evaporation is commonly used to micro-fabricate the key element of superconducting qubits—the Josephson junction. However, in conventional two-angle deposition circuit topology, unwanted stray Josephson junctions are created which contribute to dielectric loss. So far, this could be avoided by shorting the stray junctions with a so-called bandage layer deposited in an additional lithography step, which may further contaminate the chip surface. Here, we present an improved shadow evaporation technique allowing one to fabricate sub-micrometer-sized Josephson junctions together with bandage layers in a single lithography step. We also show that junction aging is significantly reduced when junction electrodes are passivated in an oxygen atmosphere directly after deposition.

Josephson junction
Micro fabrication
Shadow evaporation technique
Superconducting qubit
Superconductivity
Thin film
Transmon

http://resolver.tudelft.nl/uuid:cd2ba71f-6c42-4451-98f8-81a8b6c81fec

https://doi.org/10.1088/1361-6668/ac2a6d

0953-2048

Superconductor Science & Technology, 34 (12)

Institutional Repository

journal article

© 2021 Alexander Bilmes, Alexander K. Händel, S. Volosheniuk, Alexey V. Ustinov, Jürgen Lisenfeld