Fabrication artifacts and parallel loss channels in metamorphic epitaxial aluminum superconducting resonators

Richardson, C. J. K.; Siwak, Nathan; Hackley, Justin C.; Keane, Z.K.; Robinson, J.E.; Arey, Bruce W.; Arslan, Ilke; Palmer, B. S.

doi:10.1088/0953-2048/29/6/064003

Cited by 43 publications

(29 citation statements)

References 45 publications

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“…The resonators fabricated with either the chemical or the physical surface treatment show an improvement over unprocessed devices; a combination of the two treatments results in the biggest improvement with Q i ≈ 0.8 million at T ∼ 10 mK and n ph ∼ 1 and a time average F tan δ TLS ∼ 3.5 × 10 −7 or, equivalently, an average TLS quality factor Q TLS ∼ 3 million at T ∼ 10 mK and n ph ∼ 10. Aside from characterizing the effects of each individual surface treatment, we demonstrate that a standard electron-beam evaporation system with in situ annealing capabilities allows us to reach similar or higher resonator quality compared to an MBE system [37].…”

Section: Introductionmentioning

confidence: 99%

Substrate surface engineering for high-quality silicon/aluminum superconducting resonators

Earnest

Béjanin

McConkey

et al. 2018

Supercond. Sci. Technol.

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Quantum bits (qubits) with long coherence times are an important element for the implementation of medium-and large-scale quantum computers. In the case of superconducting planar qubits, understanding and improving qubits' quality can be achieved by studying superconducting planar resonators. In this Paper, we fabricate and characterize coplanar waveguide resonators made from aluminum thin films deposited on silicon substrates. We perform three different substrate treatments prior to aluminum deposition: One chemical treatment based on a hydrofluoric acid clean; one physical treatment consisting of a thermal annealing at 880 • C in high vacuum; one combined treatment comprising both the chemical and the physical treatments. The aim of these treatments is to remove the two-level state defects hosted by the native oxides residing at the various sample's interfaces. We first characterize the fabricated samples through cross-sectional tunneling electron microscopy acquiring electron energy loss spectroscopy maps of the samples' cross sections. These measurements show that both the chemical and the physical treatments almost entirely remove native silicon oxide from the substrate surface and that their combination results in the cleanest interface. We then study the quality of the resonators by means of microwave measurements in the "quantum regime", i.e., at a temperature T ∼ 10 mK and at a mean microwave photon number n ph ∼ 1. In this regime, we find that both surface treatments independently improve the resonator's intrinsic quality factor and that the highest quality factor is obtained for the combined treatment, Q i ∼ 0.8 million. Finally, we find that the TLS quality factor averaged over a time period of 3 h is ∼ 3 million at n ph ∼ 10, indicating that substrate surface engineering can potentially reduce the TLS loss below other losses such as quasiparticle and vortex loss.

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Section: Introductionmentioning

confidence: 99%

Substrate surface engineering for high-quality silicon/aluminum superconducting resonators

Earnest

Béjanin

McConkey

et al. 2018

Supercond. Sci. Technol.

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“…1,4 In addition, the ultra-high vacuum environment used in epitaxial growth allows for lower TLS loss attributed to cleaner interfaces between materials. 5,6 The discovery of a low-loss superconductor/dielectric/superconductor trilayer would allow the implementation of scalable, high-performance quantum computing designs such as the merged-element transmon. 7 Because the epitaxial growth of GaAs and Al/GaAs heterostructures is well-established, [8][9][10][11] GaAs is a natural candidate for epitaxial growth for superconducting quantum devices.…”

Section: Introductionmentioning

confidence: 99%

Boulder-Cryogenic-Quantum-Testbed/data: Data for "Dielectric loss in epitaxial Al/GaAs/Al trilayers for superconducting circuits"

McRae

2020

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Epitaxially-grown superconductor/dielectric/superconductor trilayers have the potential to form high-performance superconducting quantum devices and may even allow scalable superconducting quantum computing with low-surface-area qubits such as the merged-element transmon. In this work, we measure the power-independent loss and two-level-state (TLS) loss of epitaxial, wafer-bonded, and substrate-removed Al/GaAs/Al trilayers by measuring lumped element superconducting microwave resonators at millikelvin temperatures and down to single photon powers. The power-independent loss of the device is (4.8 ± 0.1) × 10 −5 and resonator-induced intrinsic TLS loss is (6.4 ± 0.2) × 10 −5 . Dielectric loss extraction is used to determine a lower bound of the intrinsic TLS loss of the trilayer of 7.2 × 10 −5 . The unusually high power-independent loss is attributed to GaAs's intrinsic piezoelectricity.

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“…[11] (similar to the works in Refs. [12][13][14][15]), we have fabricated and characterized loss in CPW resonators made from thin-film Al on Si substrates. In particular, we have cleaned a Si substrate before Al deposition using a chemical treatment based on a hydrofluoric (HF) acid followed by a physical treatment based on a thermal annealing at 880 in high vacuum.…”

Section: Introductionmentioning

confidence: 99%

Improving the Time Stability of Superconducting Planar Resonators

et al. 2019

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Quantum computers are close to become a practical technology. Solid-state implementations based, for example, on superconducting devices strongly rely on the quality of the constituent materials. In this work, we fabricate and characterize superconducting planar resonators in the microwave range, made from aluminum films on silicon substrates. We study two samples, one of which is unprocessed and the other cleaned with a hydrofluoric acid bath and by heating at 880 in high vacuum. We verify the efficacy of the cleaning treatment by means of scanning transmission electron microscope imaging of samples' cross sections. From 3 -long resonator measurements at 10 and with 10 photonic excitations, we estimate the frequency flicker noise level using the Allan deviation and find an approximately tenfold noise reduction between the two samples; the cleaned sample shows a flicker noise power coefficient for the fractional frequency of 0.23 10 15 . Our preliminary results follow the generalized tunneling model for two-level state defects in amorphous dielectric materials and show that suitable cleaning treatments can help the operation of superconducting quantum computers.

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Fabrication artifacts and parallel loss channels in metamorphic epitaxial aluminum superconducting resonators

Cited by 43 publications

References 45 publications

Substrate surface engineering for high-quality silicon/aluminum superconducting resonators

Substrate surface engineering for high-quality silicon/aluminum superconducting resonators

Boulder-Cryogenic-Quantum-Testbed/data: Data for "Dielectric loss in epitaxial Al/GaAs/Al trilayers for superconducting circuits"

Improving the Time Stability of Superconducting Planar Resonators

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