Superconducting Circuit Elements for Protected Qubits
ORAL
Abstract
We present experimental progress in microfabricating superconducting circuit elements for noise-protected qubits, specifically the 0-π qubit [1]. Our approach involves developing granular aluminum Josephson junctions, superinductors, and capacitors with two-dimensional and three-dimensional [2-4] designs. We've created a process to deposit aluminum under controlled oxygen pressures, enabling granular aluminum (Tc ~ 1.95 K) with tunable sheet resistance (400-1000 Ω/square). Material characterization of granular aluminum includes a comprehensive comparison of constriction junctions low-frequency measurements to RF using an RF-SQUID circuit, along with film quality analysis, room temperature and low-temperature electrical transport measurements. By integrating experimental fabrication with microwave simulations, our findings aim to enhance qubit performance through materials engineering, addressing challenges in minimizing decoherence mechanisms and parasitic effects while ensuring robust noise protection.
*This work was supported by the LDRD program at Sandia National Laboratories, a multimission laboratory managed and operated by NTESS under DOE NNSA contract DE-NA0003525. This work was performed in part at CINT, a U.S. DOE Office of Basic Energy Sciences user facility.
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Publication: [1] P. Brooks, A. Kitaev, J. Preskill, Protected gates for superconducting qubits, Phys. Rev. A 87, 052306 (2013).
[2] A.P. McFadden et al, NPJ Quantum Info 11, 11 (2025)
[3] A. Goswami et al, Applied Physics Letters 121, 064001 (2022)
[4] P.S. Finnegan et al, Mat Sci Semi Process 92, 80 (2019)
Presenters
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Sueli D Skinner Ramos
- Sandia National Laboratories