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arXiv · 2603.25258

Superconducting Parallel-Plate Resonators for the Detection of Single Electron Spins

André Pscherer·Jannes Liersch·Patrick Abgrall·Andrew D. Beyer·Fabien Defrance·Sunil R. Gowala·Hélène Le Sueur·James O'Sullivan·Emmanuel Flurin·Patrice Bertet
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Abstract

We introduce a multilayer superconducting microwave resonator with sub-Ohm impedance optimized for high coupling strength to single electron spins. The design minimizes the magnetic far-field and therefore achieves a Purcell factor $F_P > 10^{15}$. We show several ways to fabricate this type of resonator and present resonators with an intrinsic $Q$-factor exceeding $2 \cdot 10^4$ at the single-photon level. We further characterize these resonators in magnetic fields up to $500 \, \text{mT}$. Finally, we evaluate the impact of the achievable Purcell factor on single-spin detection through photon counting and dispersive readout.

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André Pscherer, Jannes Liersch, Patrick Abgrall, Andrew D. Beyer, Fabien Defrance, Sunil R. Gowala, Hélène Le Sueur, James O'Sullivan, Emmanuel Flurin, Patrice Bertet. 2026-03-26. Superconducting Parallel-Plate Resonators for the Detection of Single Electron Spins. https://arxiv.org/abs/2603.25258

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