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On-chip microwave sensing of quasiparticles in tantalum superconducting circuits on silicon for scalable quantum technologies
🤖 AI Summary
Non-equilibrium quasiparticles constitute a critical bottleneck limiting the performance and scalability of superconducting quantum circuits, inducing microwave loss and degrading resonator quality factors (Q) and qubit coherence times. This work reports the first on-chip, in situ microwave quasiparticle detection at the single-photon level in high-Q α-tantalum (α-Ta) coplanar waveguide resonators fabricated on silicon, combined with millikelvin-temperature-dependent characterization to quantitatively elucidate the correlation between quasiparticle density and microwave loss. Experimentally, the quasiparticle density in α-Ta is found to be approximately one-third that of niobium nitride (NbN), corresponding to a significantly enhanced intrinsic quality factor. This study establishes α-Ta as a novel low-quasiparticle-density, low-loss superconducting material and introduces an on-chip quasiparticle sensing paradigm tailored for high-coherence quantum devices.
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Application Category
📝 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 α-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 α-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.
Problem
Research questions and friction points this paper is trying to address.
Mitigating non-equilibrium quasiparticles limiting superconducting quantum circuits
Measuring quasiparticle density in tantalum resonators on silicon
Reducing microwave losses to improve qubit coherence times
Innovation
Methods, ideas, or system contributions that make the work stand out.
On-chip microwave quasiparticle sensing
Benchmarking quasiparticle density across materials
Scalable platform for improved coherence engineering
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