Low loss hybrid Nb/Au superconducting resonators for quantum circuit applications

Abstract

Superconducting resonators play a crucial role in the development of quantum technologies such as quantum computing or high performance detectors. Yet, one of their main limitations regarding to noise and sensitivity is the interaction with two-level systems present in oxide layers in the device. Focused on mitigating this problem, we study a superconducting device combining a 100 nm niobium (Nb) circuit with a 10 nm gold (Au) capping layer. Our investigation covers a wide range of temperatures and driving powers, revealing that adding the Au layer reduces the density of two-level system defects while maintaining a very high quality factor. Moreover, an increase in the non-linearity response is also observed. Our findings suggest the potential of Nb/Au lumped element resonators as versatile and promising tools for advancing superconducting quantum technologies.

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Cited by in corpus (6)

• High temporal stability of niobium superconducting resonators by surface passivation with organophosphonate self-assembled monolayers
• A Study of Superconducting Behavior in Ruthenium Thin Films
• Fabrication effects on Niobium oxidation and surface contamination in Niobium-metal bilayers using X-ray photoelectron spectroscopy
• In situ Al${}_2$O${}_3$ passivation of epitaxial tantalum and aluminum films enables long-term stability in superconducting microwave resonators
• Enhanced Tantalum Superconducting Resonator Performance via All-Surface Organic Monolayer Passivation
• Vortex Pinning in Niobium covered by a thin polycrystalline Gold