Realization of superconducting phase elements with arbitrary values using magnetic Josephson junctions and their applications to superconducting circuits

• Project/Area Number: 18K04291
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21060:Electron device and electronic equipment-related
• Research Institution: Daido University
• Principal Investigator: Akaike Hiroyuki 大同大学, 工学部, 教授 (20273287)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2018: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 超伝導デバイス / 超伝導集積回路 / 磁性ジョセフソン接合 / デバイス作製技術 / 窒化物超伝導体 / 電子デバイス・機器 / 超伝導材料・素子 / スピントロニクス / 位相制御

Outline of Final Research Achievements

In this study, we investigated characteristics of the superconducting phase shift elements with arbitrary values based on magnetic Josephson pi-junctions to develop superconducting phase shift technologies which are useful for superconducting digital circuits. Furthermore, we studied the effects of an introduction of the elements on the operation and performance of the circuits, and found that control of the polarity of the phase shift of them is crucial. We also developed a novel Josephson tunnel junction with a superconducting NbTiN material which has a long magnetic penetration depth effective in miniaturization of the elements.

Academic Significance and Societal Importance of the Research Achievements

超伝導位相シフト技術は、超低消費電力性を特長とする超伝導集積回路や量子コンピュータに使われる超伝導量子回路において、非常に重要な技術となりうる。本研究で検討した素子は、従来のジョセフソンπ-接合単体では位相シフト量がπとなるのに対して、π/2程度のものからπ程度のものまで種々の位相シフト量を実現できる。本成果は、この素子の実現可能性や回路への適用可能性を示すものであり、超伝導位相シフト技術の発展につながることから、その学術的意義は大きい。

Research Products

• [Journal Article] ジョセフソンπ接合を用いた超伝導位相シフタとその回路応用 (2020)
  • Author(s): 赤池 宏之
  • Journal Title: 大同大学紀要 Volume: 55 Pages: 1-6
  • NAID: 40022268167
  • Open Access
• [Journal Article] Fabrication of NbTiN Josephson junctions with thermally oxidized Hf tunnel barriers (2019)
  • Author(s): H. Akaike、K. Munemoto、Y. Sakakibara、A. Fujimaki
  • Journal Title: IEEE Trans. on Appl. Supercond. Volume: 29 Issue: 5 Pages: 1102605-1102605
  • DOI: 10.1109/tasc.2019.2906278
  • Peer Reviewed
• [Journal Article] Relaxation method in description of RAM memory cell in RSFQ computer (2018)
  • Author(s): K. D. Pomorski, H. Akaike, A. Fujimaki, K. Rusek
  • Journal Title: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering Volume: 38 Issue: 1 Pages: 395-414
  • DOI: 10.1108/compel-06-2017-0242
  • Peer Reviewed / Int'l Joint Research
• [Presentation] 位相シフタとしてπ接合rf-SQUIDを用いた量子化磁束パラメトロン (2020)
  • Author(s): 赤池 宏之、藤巻 朗
  • Organizer: 第67回応用物理学会春季学術講演会
• [Presentation] Fabrication of NbTiN Josephson junctions with thermally oxidized Hf tunnel barriers (2018)
  • Author(s): H. Akaike, K. Munemoto, Y. Sakakibara, A. Fujimaki
  • Organizer: 2018 Applied Superconductivity Conference
  • Int'l Joint Research