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arXiv · 2402.03889

Loss and decoherence in superconducting circuits on silicon: Insights from electron spin resonance

Aditya Jayaraman·Andrey V. Danilov·Jonas Bylander·Sergey E. Kubatkin
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Abstract

Solid-state devices used for quantum computation and quantum sensing applications are adversely affected by loss and noise caused by spurious, charged two-level systems (TLS) and stray paramagnetic spins. These two sources of noise are interconnected, exacerbating the impact on circuit performance. We use an on-chip electron spin resonance (ESR) technique, with niobium nitride (NbN) superconducting resonators, to study surface spins on silicon and the effect of post-fabrication surface treatments. We identify two distinct spin species that are characterized by different spin-relaxation times and respond selectively to various surface treatments (annealing and hydrofluoric acid). Only one of the two spin species has a significant impact on the TLS-limited resonator quality factor at low-power (near single-photon) excitation. We observe a 3-to-5-fold reduction in the total density of spins after surface treatments, and demonstrate the efficacy of ESR spectroscopy in developing strategies to mitigate loss and decoherence in quantum systems.

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Aditya Jayaraman, Andrey V. Danilov, Jonas Bylander, Sergey E. Kubatkin. 2024-02-06. Loss and decoherence in superconducting circuits on silicon: Insights from electron spin resonance. https://doi.org/10.1103/physrevapplied.22.014030

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