Chemical profiles of the oxides on tantalum in state of the art superconducting circuits

Abstract

Over the past decades, superconducting qubits have emerged as one of the leading hardware platforms for realizing a quantum processor. Consequently, researchers have made significant effort to understand the loss channels that limit the coherence times of superconducting qubits. A major source of loss has been attributed to two level systems that are present at the material interfaces. We recently showed that replacing the metal in the capacitor of a transmon with tantalum yields record relaxation and coherence times for superconducting qubits, motivating a detailed study of the tantalum surface. In this work, we study the chemical profile of the surface of tantalum films grown on c-plane sapphire using variable energy X-ray photoelectron spectroscopy (VEXPS). We identify the different oxidation states of tantalum that are present in the native oxide resulting from exposure to air, and we measure their distribution through the depth of the film. Furthermore, we show how the volume and depth distribution of these tantalum oxidation states can be altered by various chemical treatments. By correlating these measurements with detailed measurements of quantum devices, we can improve our understanding of the microscopic device losses.

References in corpus (7)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Detecting arbitrary quantum errors via stabilizer measurements on a sublattice of the surface code
• Real-time quantum error correction beyond break-even
• Noise-resilient Edge Modes on a Chain of Superconducting Qubits
• Disentangling Losses in Tantalum Superconducting Circuits
• Chemical profiles of the oxides on tantalum in state of the art superconducting circuits
• Precision measurement of the microwave dielectric loss of sapphire in the quantum regime with parts-per-billion sensitivity

Cited by in corpus (15)

• Disentangling Losses in Tantalum Superconducting Circuits
• Chemical profiles of the oxides on tantalum in state of the art superconducting circuits
• Manufacturing high-Q superconducting α-tantalum resonators on silicon wafers
• Low-Loss Superconducting Resonators Fabricated from Tantalum Films Grown at Room Temperature
• Investigation of the deposition of $\alpha$-tantalum (110) films on a-plane sapphire substrate by molecular beam epitaxy for superconducting circuit
• Engineering of Niobium Surfaces Through Accelerated Neutral Atom Beam Technology For Quantum Applications
• Revealing the Origin and Nature of the Buried Metal-Substrate Interface Layer in Ta/Sapphire Superconducting Films
• Molecular beam epitaxy growth of superconducting tantalum germanide
• Reversing Hydrogen-Related Loss in $\alpha$-Ta Thin Films for Quantum Device Fabrication
• Magnetic bound states embedded in tantalum superconducting thin films
• Epitaxial α-Ta (110) film on a-plane sapphire substrate for superconducting qubits on wafer scale
• Stable and low loss oxide layer on α-Ta (110) film for superconducting qubits
• Growth and characterization of single crystal cubic TaN and hexagonal Ta${}_2$N films on c-plane Sapphire
• 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