Superconducting qubits and current standard devices using self-duality

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02215
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 21060:Electron device and electronic equipment-related
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Kazumasa Makise 国立天文台, 先端技術センター, 准教授 (60363321)
• Co-Investigator(Kenkyū-buntansha): 篠崎 文重 九州大学, 理学研究院, 名誉教授 (80117126)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 超伝導ー絶縁体転移 / 量子位相すべり / 量子細線

Outline of Final Research Achievements

We studied transport properties in magnetic fields on series of niobium titanium nitride (NbTiN) nano structure, which is consist of nanowires and small islands. Corresponding to the enhancement of superconductivity as the nanostructures cross over from 2 dimensional thin films to 1 dimensional nanowires, we confirm a negative magnetoresistance and the increases of a critical current. From the temperature dependence resistance experiments, we observe resistive tails at low temperatures due to phase slip mechanisms originate from nanowire parts. Additionally we also observed Little-Parks oscillation like behavior for nanowire with island structure. This means coexistence of two different phases of superconducting order parameter.As a result, this structure shows the possibility of application to quantum devices even with a single-layer film.

Free Research Field

超伝導デバイス

Academic Significance and Societal Importance of the Research Achievements

超伝導量子コンピュータの集積回路を構成する基本素子はジョセフソン接合と呼ばれる薄い絶縁体を超伝導体で挟んだトンネル接合である。回路として動作させるには配線層やグランドプレーン、絶縁層が必要なため、構造によっては10層程度の積層構造になり、回路を作製するために高度なプロセス技術が必要である。そこでジョセフソン接合に依存しない単層膜による集積化を実現し、超伝導量子回路の集積化を飛躍的に向上させる。