Thin film metrology and microwave loss characterization of indium and aluminum/indium superconducting planar resonators

Abstract

Scalable architectures characterized by quantum bits (qubits) with low error rates are essential to the development of a practical quantum computer. In the superconducting quantum computing implementation, understanding and minimizing materials losses is crucial to the improvement of qubit performance. A new material that has recently received particular attention is indium, a low-temperature superconductor that can be used to bond pairs of chips containing standard aluminum-based qubit circuitry. In this work, we characterize microwave loss in indium and aluminum/indium thin films on silicon substrates by measuring superconducting coplanar waveguide resonators and estimating the main loss parameters at powers down to the sub-photon regime and at temperatures between 10 and 450 mK. We compare films deposited by thermal evaporation, sputtering, and molecular beam epitaxy. We study the effects of heating in vacuum and ambient atmospheric pressure as well as the effects of pre-deposition wafer cleaning using hydrofluoric acid. The microwave measurements are supported by thin film metrology including secondary-ion mass spectrometry. For thermally evaporated and sputtered films, we find that two-level states (TLSs) are the dominating loss mechanism at low photon number and temperature. Thermally evaporated indium is determined to have a TLS loss tangent due to indium oxide of ~5x1e-05. The molecular beam epitaxial films show evidence of formation of a substantial indium-silicon eutectic layer, which leads to a drastic degradation in resonator performance.

arXiv comment10 pages main, 5 figures, 3 tables; 3 pages supplem., 3 figures

References in corpus (28)

• Quantum Computing
• State preservation by repetitive error detection in a superconducting quantum circuit
• Decoherence in Josephson Qubits from Dielectric Loss
• Coherent Josephson qubit suitable for scalable quantum integrated circuits
• Building logical qubits in a superconducting quantum computing system
• Planar Superconducting Resonators with Internal Quality Factors above One Million
• Experimental evidence for a surface distribution of two-level systems in superconducting lithographed microwave resonators
• 3D integrated superconducting qubits
• Fabrication and characterization of superconducting circuit QED devices for quantum computation
• Study of loss in superconducting coplanar waveguide resonators
• Surface loss simulations of superconducting coplanar waveguide resonators
• Scalable quantum circuit and control for a superconducting surface code
• Noise Properties of Superconducting Coplanar Waveguide Microwave Resonators
• Analysis and mitigation of interface losses in trenched superconducting coplanar waveguide resonators
• Improving the Coherence Time of Superconducting Coplanar Resonators
• A semi-empirical model for two-level system noise in superconducting microresonators
• Minimal resonator loss for circuit quantum electrodynamics
• Contribution of dielectrics to frequency and noise of NbTiN superconducting resonators
• Superconductivity in the insulating phase above the field-tuned superconductor-insulator transition in disordered indium oxide films
• Investigating surface loss effects in superconducting transmon qubits
• Temperature Dependence of the Frequency and Noise of Superconducting Coplanar Waveguide Resonators
• The Quantum Socket: Three-Dimensional Wiring for Extensible Quantum Computing
• Decoherence Dynamics of Complex Photon States in a Superconducting Circuit
• Superconducting Through-Silicon Vias for Quantum Integrated Circuits
• Transmission-line resonators for the study of individual two-level tunneling systems
• Superconducting Caps for Quantum Integrated Circuits
• Improved superconducting qubit coherence with high-temperature substrate annealing
• Thermocompression Bonding Technology for Multilayer Superconducting Quantum Circuits

Cited by in corpus (8)

• Materials loss measurements using superconducting microwave resonators
• Substrate surface engineering for high-quality silicon/aluminum superconducting resonators
• Dielectric loss extraction for superconducting microwave resonators
• Circle fit optimization for resonator quality factor measurements: point redistribution for maximal accuracy
• Manufacturing high-Q superconducting α-tantalum resonators on silicon wafers
• Material matters in superconducting qubits
• High-Density Qubit Wiring: Pin-Chip Bonding for Fully Vertical Interconnects
• Interacting Defects Generate Stochastic Fluctuations in Superconducting Qubits