On-chip microwave sensing of quasiparticles in tantalum superconducting circuits on silicon for scalable quantum technologies

• URL: http://arxiv.org/abs/2509.07669v1
• Date: Tue, 09 Sep 2025 12:36:34 GMT
• Title: On-chip microwave sensing of quasiparticles in tantalum superconducting circuits on silicon for scalable quantum technologies
• Authors: Shima Poorgholam-Khanjari, Paniz Foshat, Mingqi Zhang, Valentino Seferai, Martin Weides, Kaveh Delfanazari,
• Abstract summary: We demonstrate on-chip microwave sensing of quasiparticles in high-Q alpha-tantalum coplanar waveguide resonators on silicon.<n>We find that the quasiparticle density in alpha-Ta is approximately one-third that of NbN at equivalent normalised temperatures.
• Score: 0.10262304700896197
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The performance and scalability of superconducting quantum circuits are fundamentally constrained by non-equilibrium quasiparticles, which induce microwave losses that limit resonator quality factors and qubit coherence times. Understanding and mitigating these excitations is therefore central to advancing scalable quantum technologies. Here, we demonstrate on-chip microwave sensing of quasiparticles in high-Q {\alpha}-tantalum coplanar waveguide resonators on silicon, operated in the single-photon regime. Temperature-dependent measurements reveal persistent non-equilibrium quasiparticles at millikelvin temperatures, producing a measurable suppression of the internal quality factor (Qi) relative to theoretical expectations. By benchmarking across materials, we find that the quasiparticle density in {\alpha}-Ta is approximately one-third that of NbN at equivalent normalised temperatures (T/Tc), directly correlating with reduced microwave loss. Our methodology establishes a scalable platform for probing quasiparticle dynamics and points towards new routes for engineering superconducting circuits with improved coherence, with impact on qubit readout resonators, kinetic-inductance detectors, and emerging quantum processors and sensors.

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