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2019 Fiscal Year Annual Research Report

Protecting a single solid-state spin from a spin bath in diamond for quantum sensing

Research Project

Project/Area Number 18F18023
Research InstitutionInstitute of Physical and Chemical Research

Principal Investigator

NORI FRANCO  国立研究開発法人理化学研究所, 開拓研究本部, 主任研究員 (50415262)

Co-Investigator(Kenkyū-buntansha) LIU TAO  国立研究開発法人理化学研究所, .開拓研究本部, 外国人特別研究員
Project Period (FY) 2018-04-25 – 2020-03-31
KeywordsTopological insulator / Non-HermitianTopological / SCTopological protection / Quantum information
Outline of Annual Research Achievements

In FY2018, my research is mainly focused on the following two topics: (1) Majorana corner states in a 2D magnetic topological insulator on a high-temperature superconductor. A d-dimensional second-order topological superconductor (TSC) is characterized by topologically protected gapless (d-2) dimensional states with the usual gapped (d - 1) boundaries. In this work, we studied a second-order TSC with a 2D magnetic topological insulator proximity coupled to a high-temperature superconductor, where Majorana bound states (MBSs) are localized at the corners of a square sample with gapped edge modes. A detailed analysis, based on edge theory, revealed the origin of the existence of MBSs at the corners of the 2D sample, which results from the sign change of the Dirac mass emerging at the intersection of any two adjacent edges due to pairing symmetry. (2) Second-order topological phases in non-Hermitian systems. A d-dimensional second-order topological insulator (SOTI) can host topologically protected (d-2)-dimensional gapless boundary modes. In this work, we showed that a 2D non-Hermitian SOTI can host zero-energy modes localized only at one corner. A 3D non-Hermitian SOTI is shown to support second-order boundary modes localized not along hinges but anomalously at a corner. The usual bulk-corner (hinge) correspondence in the second-order 2D (3D) non-Hermitian system breaks down.

Research Progress Status

令和元年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和元年度が最終年度であるため、記入しない。

  • Research Products

    (4 results)

All 2019

All Journal Article (4 results) (of which Peer Reviewed: 1 results,  Open Access: 1 results)

  • [Journal Article] Second-Order Topological Phases in Non-Hermitian Systems2019

    • Author(s)
      Liu Tao、Zhang Yu-Ran、Ai Qing、Gong Zongping、Kawabata Kohei、Ueda Masahito、Nori Franco
    • Journal Title

      Physical Review Letters

      Volume: 122 Pages: 07681

    • DOI

      https://doi.org/10.1103/PhysRevLett.122.076801

    • Peer Reviewed / Open Access
  • [Journal Article] Topological band theory for non-Hermitian systems from the Dirac equation2019

    • Author(s)
      Ge Zi-Yong、Zhang Yu-Ran、Liu Tao、Li Si-Wen、Fan Heng、Nori Franco
    • Journal Title

      Physical Review B

      Volume: 100 Pages: 054105

    • DOI

      https://doi.org/10.1103/PhysRevB.100.054105

  • [Journal Article] Broad-band negative refraction via simultaneous multi-electron transitions2019

    • Author(s)
      Cheng Jing-Jing、Chu Ying-Qi、Liu Tao、Zhao Jie-Xing、Deng Fu-Guo、Ai Qing、Nori Franco
    • Journal Title

      Journal of Physics Communications

      Volume: 3 Pages: 015010~015010

    • DOI

      10.1088/2399-6528/aafe4b

  • [Journal Article] Majorana corner states in a two-dimensional magnetic topological insulator on a high-temperature superconductor2019

    • Author(s)
      Liu Tao、He James Jun、Nori Franco
    • Journal Title

      Physical Review B

      Volume: 98 Pages: 245413

    • DOI

      10.1103/PhysRevB.98.245413

URL: 

Published: 2021-01-27  

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