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Electrically controlled spin qubit in Ge/Si nanowire with fast radio-frequency readout

Research Project

Project/Area Number 17K14076
Research Category

Grant-in-Aid for Young Scientists (B)

Allocation TypeMulti-year Fund
Research Field Nanostructural physics
Research InstitutionInstitute of Physical and Chemical Research

Principal Investigator

SUN Jian  国立研究開発法人理化学研究所, 開拓研究本部, 客員研究員 (70792357)

Project Period (FY) 2017-04-01 – 2019-03-31
Project Status Completed (Fiscal Year 2018)
Budget Amount *help
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2017: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Keywordsspin-orbit interaction / quantum dot / nanowire / Qubit / Resonator / hole-photon coupling / quantum point contact / spin qubit / 量子デバイス / ナノデバイス
Outline of Final Research Achievements

We obtained the optimized ohmic contact to Ge/Si nanowire. With such devices, we achieved quasi-ballistic transport in the nanowire and measured quantized conductance features. The helical spin state was detected as a re-entrant conductance feature residing on conductance plateaus of 2e^2/h, which is a strong experimental support of the existence of strong spin-orbit interaction. We extracted a strong spin-orbit energy of 2.1 meV and g-factor of 3.6 (Nano Lett. 2018).
We also fabricated the gate-defined quantum dots in nanowire with sub-100 nm pitch finger gates and exfoliated hBN dielectric. A microwave transmission line resonator connected to the source is utilized to for the fast readout. Moreover, the qubit energy can be separately tuned by the chemical potential difference and the tunnel coupling between the adjacent dots, thus switching on and off the coupling. The hole-photon coupling strength is evaluated to be in the magnitude of several tens of MHz. (Nano Lett. 2019)

Academic Significance and Societal Importance of the Research Achievements

We detect helical gap and a strong spin-orbit interaction in Ge/Si NW, suggesting it as a promising platform for studying Majorana physics.
We demonstrate the hole-photon coupling of 10sMHz in the Ge/Si quantum dots for future implementation of coherent hole-photon interaction in Ge/Si NWs.

Report

(3 results)
  • 2018 Annual Research Report   Final Research Report ( PDF )
  • 2017 Research-status Report
  • Research Products

    (5 results)

All 2019 2018

All Journal Article (2 results) (of which Int'l Joint Research: 2 results,  Peer Reviewed: 2 results) Presentation (3 results) (of which Int'l Joint Research: 1 results)

  • [Journal Article] Gate Tunable Hole Charge Qubit Formed in a Ge/Si Nanowire Double Quantum Dot Coupled to Microwave Photons2019

    • Author(s)
      Rui Wang, Russell S. Deacon, Jian Sun, Jun Yao, Charles M. Lieber, Koji Ishibashi
    • Journal Title

      Nano Lett.

      Volume: 19 Issue: 2 Pages: 1052-1060

    • DOI

      10.1021/acs.nanolett.8b04343

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Helical Hole State in Multiple Conduction Modes in Ge/Si Core/Shell Nanowire2018

    • Author(s)
      Jian Sun, Russell Deacon, Rui Wang, Jun Yao, Charles Lieber, Koji Ishibashi
    • Journal Title

      Nano Lett.

      Volume: 18 Issue: 10 Pages: 6144-6149

    • DOI

      10.1021/acs.nanolett.8b01799

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Presentation] Helical State in Ge/Si Core/Shell Nanowire2018

    • Author(s)
      Jian Sun
    • Organizer
      The 2nd CEMS International Symposium on Dynamics in Artificial Quantum Systems
    • Related Report
      2017 Research-status Report
    • Int'l Joint Research
  • [Presentation] Helical State in Ge/Si Core/Shell Nanowire2018

    • Author(s)
      Jian Sun
    • Organizer
      The 65th JSAP Spring Meeting
    • Related Report
      2017 Research-status Report
  • [Presentation] Helical State in Ge/Si Nanowire2018

    • Author(s)
      Jian Sun
    • Organizer
      Project Meeting on MEXT "Hybrid Quantum Systems"
    • Related Report
      2017 Research-status Report

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Published: 2017-04-28   Modified: 2020-03-30  

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