Nitrogen Plasma Passivated Niobium Resonators for Superconducting Quantum Circuits

Abstract

Microwave loss in niobium metallic structures used for superconducting quantum circuits is limited by a native surface oxide layer formed over a timescale of minutes when exposed to an ambient environment. In this work, we show that nitrogen plasma treatment forms a niobium nitride layer at the metal-air interface which prevents such oxidation. X-ray photoelectron spectroscopy confirms the doping of nitrogen more than 5 nm into the surface and a suppressed oxygen presence. This passivation remains stable after aging for 15 days in an ambient environment. Cryogenic microwave characterization shows an average filling factor adjusted two-level-system loss tangent $\mathrm{F}{\delta }_{\mathrm{TLS}}$ of $(2.9\pm 0.5)\cdot 10^{-7}$ for resonators with 3 $\mu$m center strip and $(1.0\pm 0.3)\cdot 10^{-7}$ for 20 $\mu$m center strip, exceeding the performance of unpassivated samples by a factor of four.

arXiv comment7 pages, 5 figures

References in corpus (27)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• New material platform for superconducting transmon qubits with coherence times exceeding 0.3 milliseconds
• Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits
• Planar Superconducting Resonators with Internal Quality Factors above One Million
• An analysis method for asymmetric resonator transmission applied to superconducting devices
• Microwave Dielectric Loss at Single Photon Energies and milliKelvin Temperatures
• Nitrogen and argon doping of niobium for superconducting radio frequency cavities: a pathway to highly efficient accelerating structures
• Materials loss measurements using superconducting microwave resonators
• Surface loss simulations of superconducting coplanar waveguide resonators
• Low Loss Superconducting Titanium Nitride Coplanar Waveguide Resonators
• Microwave response of vortices in superconducting thin films of Re and Al
• Solid-state qubits integrated with superconducting through-silicon vias
• Investigation of microwave loss induced by oxide regrowth in high-Q Nb resonators
• Trapping a single vortex and reducing quasiparticles in a superconducting resonator
• Atomic layer deposition of titanium nitride for quantum circuits
• Enhanced coherence of all-nitride superconducting qubits epitaxially grown on silicon substrate
• Microwave Package Design for Superconducting Quantum Processors
• Comparison of Dielectric Loss in Titanium Nitride and Aluminum Superconducting Resonators
• Proximity-Coupled Ti/TiN Multilayers for use in Kinetic Inductance Detectors
• Microwave-induced excess quasiparticles in superconducting resonators measured through correlated conductivity fluctuations
• On the quest of low temperature nitrogen infusion relevant for superconducting Nb based radio-frequency cavities
• Superconductor to weak-insulator transitions in disordered Tantalum Nitride films
• Fabrication and surface treatment of electron-beam evaporated niobium for low-loss coplanar waveguide resonators
• Atomic Layer Deposition Niobium Nitride Films for High-Q Resonators
• Localization and reduction of superconducting quantum coherent circuit losses
• Microscopic Theory of Magnetic Disorder-Induced Decoherence in Superconducting Nb Films
• Characterization of the Chemical and Electrical Properties of Defects at the Niobium-Silicon Interface

Cited by in corpus (10)

• Systematic Improvements in Transmon Qubit Coherence Enabled by Niobium Surface Encapsulation
• Formation and Microwave Losses of Hydrides in Superconducting Niobium Thin Films Resulting from Fluoride Chemical Processing
• Isotropic plasma-thermal atomic layer etching of superconducting TiN films using sequential exposures of molecular oxygen and SF${}_6/$H${}_2$ plasma
• Characterization of process-related interfacial dielectric loss in aluminum-on-silicon by resonator microwave measurements, materials analysis, and imaging
• Engineering of Niobium Surfaces Through Accelerated Neutral Atom Beam Technology For Quantum Applications
• Why Superconducting Ta Qubits Have Fewer Tunneling Two-Level Systems at the Air-Oxide Interface Than Nb Qubits
• Stable and low loss oxide layer on α-Ta (110) film for superconducting qubits
• Low-loss Nb on Si superconducting resonators from a dual-use spintronics deposition chamber and with acid-free post-processing
• Fabrication effects on Niobium oxidation and surface contamination in Niobium-metal bilayers using X-ray photoelectron spectroscopy
• Surface Optimization of Superconducting Aluminum Resonators for Robust Quantum Device Fabrication