Epitaxial α-Ta (110) film on a-plane sapphire substrate for superconducting qubits on wafer scale

Zhou, Boyi; Yang, Lina; Wang, Tao; Wang, Yu; Ding, Zengqian; Wu, Yanfu; Xiong, Kanglin; Feng, Jiagui

doi:10.35848/1347-4065/acfde6

Cited by 2 publications

(1 citation statement)

References 36 publications

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“…To demonstrate real quantum advantage, the quality and quantity of qubits need to increase simultaneously. In recent years, the coherence time (T 1 ) of Transmon qubits on plane surface has increased to hundreds of microseconds due to the improvement of material quality and fabrication methods [3][4][5][6][7] . In 2020, A. P. M. Place et al reported coherence time of exceeding 0.3 ms for the Transmon fabricated with alpha-phase tantalum lms 8 .…”

Section: Introductionmentioning

confidence: 99%

A stable and low loss oxide layer on α-Ta (110) film for superconducting qubits

Ding,

zhou,

Wang

et al. 2023

Preprint

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The dielectric loss of amorphous oxide layers is a major limiting factor for the coherent time of superconducting qubits. Usually, the surface oxides of superconductor film are lossy and unstable in air. To increase the coherence time, it is essential for qubits to have stable and low dielectric loss oxides, either as barrier or passivation layers. Here, we demonstrate that a kind of amorphous tantalum oxide on α-Ta (110) film is robust and stable by means of chemical and structural analysis. Such kind of oxide layer forms in a self-limiting process on the surface of α-Ta (110) film in piranha solution, yielding stable thickness and steady chemical composition. Quarter-wavelength coplanar waveguide resonators are made to study the loss of this oxide. One fresh resonator have a Qi of 3.0×106 in the single photon region. The Qi of most devices are higher than 2.0×106. And most of them are still over one million even after exposed to air for months. Based on these findings, we propose an all-tantalum superconducting qubit utilizing such oxide as passivation layers, which possess low dielectric loss and improved stability.

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Section: Introductionmentioning

confidence: 99%

A stable and low loss oxide layer on α-Ta (110) film for superconducting qubits

Ding,

zhou,

Wang

et al. 2023

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

Stable and low loss oxide layer on α-Ta (110) film for superconducting qubits

Ding,

Zhou,

Wang

et al. 2024

Journal of Vacuum Science &Amp; Technology B

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The presence of amorphous oxide layers can significantly affect the coherent time of superconducting qubits due to their high dielectric loss. Typically, the surface oxides of superconductor films exhibit lossy and unstable behavior when exposed to air. To increase the coherence time, it is essential for qubits to have stable and low dielectric loss oxides, either as barrier or passivation layers. In this study, we highlight the robust and stable nature of an amorphous tantalum oxide layer formed on α-Ta (110) film by employing chemical and structural analyses. Such kind of oxide layer forms in a self-limiting process on the surface of α-Ta (110) film in piranha solution, yielding stable thickness and steady chemical composition. Quarter-wavelength coplanar waveguide resonators are made to study the loss of this oxide. One resonator has a Qi of 3.0 × 106 in the single photon region. The Qi of most devices are higher than 2.0 × 106. Moreover, most of them are still over 1 × 106 even after exposed to air for months. Based on these findings, we propose an all-tantalum superconducting qubit utilizing such oxide as passivation layers, which possess low dielectric loss and improved stability.

show abstract

Epitaxial α-Ta (110) film on a-plane sapphire substrate for superconducting qubits on wafer scale

Cited by 2 publications

References 36 publications

A stable and low loss oxide layer on α-Ta (110) film for superconducting qubits

A stable and low loss oxide layer on α-Ta (110) film for superconducting qubits

Stable and low loss oxide layer on α-Ta (110) film for superconducting qubits

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