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2018 Fiscal Year Annual Research Report

Theoretical study of nonequilibrium quantum phenpmena in cold fermions

Research Project

Project/Area Number 16K05501
Research InstitutionKyoto University

Principal Investigator

川上 則雄  京都大学, 理学研究科, 教授 (10169683)

Project Period (FY) 2016-04-01 – 2019-03-31
Keywords冷却原子系 / 非平衡量子現象 / 強相関系 / 相転移
Outline of Annual Research Achievements

本年度は、冷却原子系における強相関効果に重点を置いて研究を進めた。とくに相互作用により誘起されるトポロジカル相、サウレスポンプへの相互作用の影響とブレークダウン、引力ハバード相互作用による超伝導・電荷密度波・スピン密度波の競合などに関して研究成果が得られた。
(1)相互作用により誘起される新奇トポロジカル相: トポロジカル相に関する、残された重要な課題の一つにトポロジカル分類の相互作用によるリダクションがある。しかしながら、これを検証する実験舞台はほとんど提案されていなかった。本研究では、冷却原子系を用いて、相互作用による分類のZ->Z4へのリダクションの舞台を提案し、実験的な観測方法を詳細に調べた。
(2)サウレスポンプへの相互作用の影響:近年、サウレスポンプは冷却原子系で実現され大きな興味を集めたが、これまで相互作用のない自由原子系が対象であった。ここでは、サウレスポンプへの相互作用効果を系統的に調べた。相互作用がある閾値を超えるとトポロジカル相のギャップが閉じ、サウレスポンプがブレークダウンすることを示した。さらに相互作用の効果はエッジ状態に顕著に表れることを示した。ここでの結果は従来の非摂動的な扱いを超えたトポロジカルポンプの安定性の系統的な議論を可能とするものである。
(3)近藤格子系における超伝導・電荷密度波・スピン密度波の競合:冷却フェルミ原子系では近藤格子模型の実現が近い将来可能になると考えられている。フェッシュバッハ共鳴を用いることで遍歴フェルミ原子間の引力相互作用を変化させることが可能となる。ここでは、引力相互作用を含む近藤格子系で超伝導・電荷密度波・スピン密度波の競合を調べた。その結果、超伝導とスピン密度波の共存相を見出し、超伝導がスピン密度波を増強することを明らかにした。
(4)この他にも、時間結晶や非エルミート強相関系の研究などにも成果が得られた。

  • Research Products

    (27 results)

All 2019 2018

All Journal Article (8 results) (of which Peer Reviewed: 8 results) Presentation (19 results) (of which Int'l Joint Research: 17 results,  Invited: 9 results)

  • [Journal Article] Symmetry-protected exceptional rings in two-dimensional correlated systems with chiral symmetry2019

    • Author(s)
      T. Yoshida, R. Peters, N. Kawakawmi, and Y. Hatsugai
    • Journal Title

      Phys. Rev. B

      Volume: 99 Pages: 121101(R)-1-5

    • DOI

      10.1103/PhysRevB.99.121101

    • Peer Reviewed
  • [Journal Article] Interplay between Charge, Magnetic and Superconducting Order in a Kondo Lattic with an Attractive Hubbard Interaction2018

    • Author(s)
      B. Lechtenberg, R. Peters and N. Kawakami,
    • Journal Title

      Phys. Rev. B

      Volume: 98 Pages: 195111-1-11

    • DOI

      10.1103/PhysRevB.98.195111

    • Peer Reviewed
  • [Journal Article] Non-Hermitian Kondo Effect in Ultracold Alkaline-Earth Atoms2018

    • Author(s)
      M. Nakagawa, N. Kawakami, and M. Ueda
    • Journal Title

      Phys. Rev. Lett.

      Volume: 121 Pages: 203001-1-6

    • DOI

      10.1103/PhysRevLett.121.203001

    • Peer Reviewed
  • [Journal Article] Spatial-Translation-Induced Discrete Time Crystals2018

    • Author(s)
      K. Mizuta, K. Takasan, M. Nakagawa, and N. Kawakami
    • Journal Title

      Phys. Rev. Lett.

      Volume: 121 Pages: 093001-1-6

    • DOI

      10.1103/PhysRevLett.121.093001

    • Peer Reviewed
  • [Journal Article] Non-Hermitian perspective of the band structure in heavy-fermion systems2018

    • Author(s)
      T. Yoshida, R. Peters and N. Kawakami
    • Journal Title

      Phys. Rev. B

      Volume: 98 Pages: 035141-1-7

    • DOI

      10.1103/PhysRevB.98.035141

    • Peer Reviewed
  • [Journal Article] Topological properties of magnetically ordered heavy-fermion systems in the presence of mirror symmetry2018

    • Author(s)
      K. Kimura, T. Yoshida, and N. Kawakami
    • Journal Title

      J. Phys. Soc. Jpn.

      Volume: 87 Pages: 084705-1-9

    • DOI

      10.7566/JPSJ.87.084705

    • Peer Reviewed
  • [Journal Article] Magnetic states in a three-dimensional topological Kondo insulator2018

    • Author(s)
      R. Peters, T. Yoshida, and N. Kawakami
    • Journal Title

      Phys. Rev. B

      Volume: 98 Pages: 075104-1-9

    • DOI

      10.1103/PhysRevB.98.075104

    • Peer Reviewed
  • [Journal Article] Reduction of Topological Z Classification in Cold-Atom Systems2018

    • Author(s)
      T. Yoshida, I. Danshita, P. Robert, N. Kawakami
    • Journal Title

      Physical Review Letters

      Volume: 121 Pages: 025301-1-6

    • DOI

      10.1103/PhysRevLett.121.025301

    • Peer Reviewed
  • [Presentation] 強相関系における非エルミート量子現象2019

    • Author(s)
      川上則雄
    • Organizer
      非エルミート系および光学実験に関する研究会
    • Invited
  • [Presentation] Topological Properties of mirror symmetric Kondo half-metals2019

    • Author(s)
      Kazuhiro Kimura, Tsuneya Yoshida and Norio Kawakami
    • Organizer
      APS March Meetig 2019
    • Int'l Joint Research
  • [Presentation] Spatial-Translation-Induced Discrete Time Crystals2019

    • Author(s)
      Kaoru Mizuta, Kazuaki Takasan, Masaya Nakagawa, and Norio Kawakami
    • Organizer
      APS March Meetig 2019
    • Int'l Joint Research
  • [Presentation] Applications of Electron Hydrodynamics to Nonlocal and Nonlinear Optical Effects2019

    • Author(s)
      Riki Toshio, Kazuaki Takasan, Norio Kawakami
    • Organizer
      Topological Phases and Functionality of Correlated Electron Systems 2019
    • Int'l Joint Research
  • [Presentation] Fate of loss-induced superconductivity studied by non-Hermitian mean field theory2019

    • Author(s)
      Kazuki Yamamoto and Norio Kawakami
    • Organizer
      Topological Phases and Functionality of Correlated Electron Systems
    • Int'l Joint Research
  • [Presentation] Correlation effects in non-Hermitian quantum systems2018

    • Author(s)
      N. Kawakami
    • Organizer
      Japan-Swiss Workshop on Trends in Theory of Correlated Materials
    • Int'l Joint Research / Invited
  • [Presentation] Floquet Topological Phase Transitions in Correlated Systems2018

    • Author(s)
      N. Kawakami
    • Organizer
      The Second TMS-PKU Alliance Workshop on Topological Materials and Quantum Materials
    • Int'l Joint Research / Invited
  • [Presentation] Laser induced topological phases in correlated systems2018

    • Author(s)
      N. Kawakami
    • Organizer
      Erice Workshop 2018: Majorana Fermions and Topological Materials Science
    • Int'l Joint Research / Invited
  • [Presentation] Emergent topological phases in correlated systems by laser irradiation2018

    • Author(s)
      N. Kawakami
    • Organizer
      New Trends in Topological Insulators
    • Int'l Joint Research / Invited
  • [Presentation] Floquet topological phases in correlated electron systems2018

    • Author(s)
      N, Kawakami
    • Organizer
      KIAS-KAIST Workshop on Topology an Correlation
    • Int'l Joint Research / Invited
  • [Presentation] Laser-induced topological phases in correlated systems2018

    • Author(s)
      N. Kawakami
    • Organizer
      62nd CEMS Colloquium
    • Int'l Joint Research / Invited
  • [Presentation] 固体物理におけるトポロジー2018

    • Author(s)
      川上則雄
    • Organizer
      ImPACT未来開拓研究会2018
    • Invited
  • [Presentation] Topological Properties of Magnetically Ordered Heavy-Fermion Systems: AFM phase & FM phase2018

    • Author(s)
      Kazuhiro Kimura, Tsuneya Yoshida and Norio Kawakami
    • Organizer
      BEC2018
    • Int'l Joint Research
  • [Presentation] Hydrodynamic optical response of electron fluids in ultrapure metals2018

    • Author(s)
      Riki Toshio, Kazuaki Takasan, Norio Kawakami
    • Organizer
      International Symposium on Frontiers of Quantum Transport in Nano Science
    • Int'l Joint Research
  • [Presentation] Enhancement of the superconducting gap induced by dissipation2018

    • Author(s)
      Kazuki Yamamoto and Norio Kawakami
    • Organizer
      International Symposium on Frontiers of Quantum Transport in Nano Science
    • Int'l Joint Research
  • [Presentation] Topological mirror Kondo semi-metals and half-metals in two-dimensional magnetic systems2018

    • Author(s)
      Kazuhiro Kimura, Tsuneya Yoshida and Norio Kawakami
    • Organizer
      International Conference on Magnetism
    • Int'l Joint Research
  • [Presentation] Time crystals realized by spatial translation and its symmetry breaking2018

    • Author(s)
      Kaoru Mizuta, Kazuaki Takasan, Masaya Nakagawa, and Norio Kawakami
    • Organizer
      International Conference on Magnetism
    • Int'l Joint Research
  • [Presentation] Spatial-Translation-Induced Floquet Time Crystals2018

    • Author(s)
      Kaoru Mizuta, Kazuaki Takasan, Masaya Nakagawa, and Norio Kawakami
    • Organizer
      YITP workshop "Floquet theory: Fundamentals and Applications"
    • Int'l Joint Research / Invited
  • [Presentation] Theoretical study of 2D topological Kondo insulator in antiferromagnetic phase2018

    • Author(s)
      Kazuhiro Kimura, Tsuneya Yoshida and Norio Kawakami
    • Organizer
      TMS-EPiQS 2nd Alliance Workshop: Topological magnets and topological superconductors
    • Int'l Joint Research

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Published: 2019-12-27  

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