21st Patras Workshop on Axions, WIMPs and WISPs

Super conducting circuits for future dark matter searches

Not scheduled

20m

University of Western Australia

Poster Presentation

Speaker

William Campbell (The University of Queensland)

Description

Recent experiments have suggested future particle dark matter searches can be improved and even performed entirely with superconducting circuits [1]. However, superconducting qubits are highly susceptible to quasiparticle generation from background ionizing radiation, which produces energetic phonons capable of breaking Cooper pairs and inducing correlated errors. Following the observation of cosmic-ray–induced error bursts in large-scale superconducting qubit arrays [2], recent efforts have explored reducing the impact of ionizing radiation through gap engineering ,phonon downconversion, material optimization, and underground operation [3,4,5]. However, scalable on-chip suppression of phonon-mediated quasiparticles remains an open challenge.

In this work, we present the design and fabrication of transmon qubits on a silicon-on-insulator (SOI) platform incorporating suspended membranes that act as acoustic low-pass filters. This architecture enables systematic investigation of phonon transport and its role in radiation-induced decoherence. We report successful fabrication and characterization of SOI-based transmons with parity-switching rate approaching 0.1 Hz. These results demonstrate the compatibility of membrane-supported architectures with standard superconducting qubit fabrication processes. The proposed architecture can be implemented alongside other mitigation strategies to further reduce the impact of ionizing radiation, thus reducing potential background signals in future dark matter experiments.

[1]: Dixit, A., Chakram, S., He, K., Agrawal, A., Naik, R., Schuster, D., & Chou, A. (2021). Searching for Dark Matter with a Superconducting Qubit. Phys. Rev. Lett., 126, 141302.

[2]: McEwen, M., Faoro, L., Arya, K. et al. Resolving catastrophic error bursts from cosmic rays in large arrays of superconducting qubits. Nat. Phys. 18, 107–111 (2022).
[3]: T. Yamamoto, Y. Nakamura, Yu. A. Pashkin, O. Astafiev, and J. S. Tsai, "Parity effect in superconducting aluminum single electron transistors with spatial gap profile controlled by film thickness," Appl. Phys. Lett. 88, 212509 (2006).
[4]: Loer, B., et al. Abatement of ionizing radiation for superconducting quantum devices. Nat. Commun. 15, (2024).
[5]: Bargerbos, A., et al. Mitigation of quasiparticle loss in superconducting qubits by phonon scattering. Phys. Rev. Lett. 131, (2023).