Overcoming material and size limitations of niobium-based trilayer Josephson junctions using an airbridge process: Part 1 - Fabrication
ORAL
Abstract
Niobium-based trilayer Josephson junctions enable superconducting qubits to operate at ~1 K and in the millimeter-wave range. Recent works using Nb-Al-AlOx-Al-Nb junctions have successfully realized high-coherence qubits [1] and a millimeter-wave qubit [2]. To make this process compatible with a wider variety of barrier materials and smaller junction sizes, we have developed an airbridge-like junction process using grayscale electron-beam lithography of resist spacer, permitting junction contact areas down to ~100 nm while eliminating the need for harsh chemical etching. This process also allows for the exploration of promising alternative barrier materials such as HfOx.
In this first part of our two-part talk, we will describe this airbridge fabrication process and present initial measurements.
[1] Anferov et al., Phys. Rev. Applied 21, 024047 (2024)
[2] Anferov et al., PRX Quantum 6, 020336 (2025)
In this first part of our two-part talk, we will describe this airbridge fabrication process and present initial measurements.
[1] Anferov et al., Phys. Rev. Applied 21, 024047 (2024)
[2] Anferov et al., PRX Quantum 6, 020336 (2025)
*This work was supported by AFOSR under grant FA9550-23-1-0692. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF) RRID:SCR_023230, supported by the National Science Foundation under award ECCS-2026822, and nano@Stanford labs, which are supported by the National Science Foundation as part of the National Nanotechnology Coordinated Infrastructure under award ECCS-2026822.
–
Presenters
-
Yoshiki Sunada
- Stanford University