量子流体力学における「ゆらぎと構造の協奏」

• Project Area: Synergy of Fluctuation and Structure:Foundation of Universal Laws in Nonequilibrium Systems
• Project/Area Number: 16H00807
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: Osaka City University
• Principal Investigator: 坪田 誠 大阪市立大学, 大学院理学研究科, 教授 (10197759)
• Project Period (FY): 2016-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000); Fiscal Year 2017: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000); Fiscal Year 2016: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
• Keywords: 量子乱流 / 量子渦 / 超流動ヘリウム / 原子気体ボース・アインシュタイン凝縮 / 低温物性 / 物性理論

Outline of Annual Research Achievements

低温物理学における重要テーマの一つである量子流体力学を、非線形・非平衡物理学の観点から、理論的および数値的に研究する。舞台となる系は、原子気体ボース・アインシュタイン凝縮体(BEC)および超流動ヘリウムである。今年度は特に、超流動ヘリウムの２流体モデルの完全結合ダイナミクスに注力した。系が非粘性の超流体と粘性を持つ常流体の混合であるとする２流体モデルは、1941年にティサとランダウによって提案されて以来、低温物理の様々な現象の理解に貢献して来たが、２流体の完全結合ダイナミクスは、ごく簡単な場合を除いて、ほとんど研究されたことがない。本研究は超流動が量子乱流を構成している場合を想定し、超流動は量子渦糸モデルで、常流体はナヴィエ・ストークス方程式で扱い、両者を相互摩擦で結合させ、熱対向流を想定した数値計算を行った。正方形管を想定した。量子渦が発達し渦タングルを作ると、それが大きな相互摩擦を生み、層流を想定した常流動速度場の大きな変形を引き起こすことを初めて示した。この変形を特徴付けるために、通常にレイノルズ数に加えて、新規なパラメータを導入し、それが有効に働くことを確認した。この結果は、近年、アメリカのグループによる可視化実験の結果と整合性がある。

Research Progress Status

29年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

29年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] フロリダ州立大学(米国)
• [Int'l Joint Research] 国立台湾師範大学(台湾)
• [Journal Article] Three-Dimensional Coupled Dynamics of the Two-Fluid Model in Superfluid He4: Deformed Velocity Profile of Normal Fluid in Thermal Counterflow (2018)
  • Author(s): Yui Satoshi、Tsubota Makoto、Kobayashi Hiromichi
  • Journal Title: Physical Review Letters Volume: 120 Issue: 15 Pages: 155301-155301
  • DOI: 10.1103/physrevlett.120.155301
  • Peer Reviewed
• [Journal Article] Flows with fractional quantum circulation in Bose-Einstein condensates induced by nontopological phase defects (2018)
  • Author(s): Kanai Toshiaki、Guo Wei、Tsubota Makoto
  • Journal Title: Physical Review A Volume: 97 Issue: 1 Pages: 013612-013612
  • DOI: 10.1103/physreva.97.013612
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Numerical Studies of Quantum Turbulence (2017)
  • Author(s): Tsubota Makoto、Fujimoto Kazuya、Yui Satoshi
  • Journal Title: Journal of Low Temperature Physics Volume: 188 Issue: 5-6 Pages: 119-189
  • DOI: 10.1007/s10909-017-1789-8
  • Peer Reviewed
• [Journal Article] Quantum crystallography of Rydberg-dressed Bose gases on a square lattice (2017)
  • Author(s): Che-hsiu Hsueh, Wen-Chin Wu, Makoto Tsubota
  • Journal Title: Physical Review A Volume: 95 Issue: 1
  • DOI: 10.1103/physreva.95.013631
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Coflow turbulence of superfluid 4He in a square channel: Vortices trapped on a cylindrical attractor (2016)
  • Author(s): Shinichi Ikawa, makoto Tsubota
  • Journal Title: Physical Review B Volume: 93 Issue: 18
  • DOI: 10.1103/physrevb.93.184508
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Quantum Turbulence in Coflow of Superfluid 4He (2016)
  • Author(s): S.Ikawa, M. Tsubota
  • Journal Title: Journal of Low Temperature Physics Volume: 183 Issue: 3-4 Pages: 230-237
  • DOI: 10.1007/s10909-016-1578-9
  • Peer Reviewed / Acknowledgement Compliant
• [Presentation] Numerical Simulation of Quantum Turbulence (2018)
  • Author(s): Makoto Tsubota
  • Organizer: DPG Spring Meeting and EPS-CMD27
  • Int'l Joint Research / Invited
• [Presentation] Topics of glasses in atomic Bose-Einstein condensates (2017)
  • Author(s): Makoto Tsubota
  • Organizer: Glasses and Related Nonequilibrium Systems
  • Place of Presentation: 大阪大学(大阪府豊中市待兼山町)
  • Year and Date: 2017-03-21
  • Int'l Joint Research / Invited
• [Presentation] Hydrodynamics and turbulence in quantum fluids (2017)
  • Author(s): Makoto Tsubota
  • Organizer: The 4th East Asia Joint Seminars on Statistical Physics
  • Int'l Joint Research / Invited
• [Presentation] Recent topics of quantum turbulence (2017)
  • Author(s): Makoto Tsubota
  • Organizer: Hybrid Photonics & Materials International Conference
  • Int'l Joint Research / Invited
• [Presentation] Fully coupled dynamics of two-fluid model in thermal counterflow: deformation of the Poiseuille normal fluid profile (2017)
  • Author(s): Makoto Tsubota, Satoshi Yui, Hiromichi Kobayashi
  • Organizer: 28th International Conference on Low Temperature Physics
  • Int'l Joint Research
• [Presentation] Quantum Turbulence in Bose-Einstein Condensates (2016)
  • Author(s): Makoto Tsubota
  • Organizer: Topological Effects in Ultra-Cold Atoms
  • Place of Presentation: Federal University of Rio Grande do Norte, Brazil
  • Year and Date: 2016-11-14
  • Int'l Joint Research / Invited
• [Presentation] Inhomogeneous quantum turbulence in a channel (2016)
  • Author(s): M. Tsubota, S. Yui,and S. Ikawa
  • Organizer: QFS2016: Internatinal Conference on Quantum Fluids and Solids
  • Place of Presentation: Prague, Czech Republic
  • Year and Date: 2016-08-10
  • Int'l Joint Research
• [Presentation] Inhomogeneous quantum turbulence and the dynamics of quantized vortices (2016)
  • Author(s): Makoto Tsubota
  • Organizer: Dynamics of Electron Vortex and Spin Vortex
  • Place of Presentation: 豊田理研(名古屋市西区則武新町)
  • Year and Date: 2016-07-01
  • Int'l Joint Research / Invited
• [Presentation] Inhomogeneous quantum turbulence in a channel (2016)
  • Author(s): Makoto Tsubota
  • Organizer: New Challenges in Mathematical Modelling and Numerical Simulation of Superfluids
  • Place of Presentation: Marseille, France
  • Year and Date: 2016-06-27
  • Int'l Joint Research / Invited
• [Presentation] Numerical simulation of quantum turbulence in superfluid helium -Inhomogeneous quantum turbulence- (2016)
  • Author(s): Makoto Tsubota
  • Organizer: Helicity,Structures and Singularity in Fluid and Plasma Dynamics"
  • Place of Presentation: Venice, Italy
  • Year and Date: 2016-04-11
  • Int'l Joint Research / Invited
• [Book] 量子流体力学 (2018)
  • Author(s): 坪田 誠、小林 未知数、竹内 宏光、笠松 健一
  • Total Pages: 338
  • Publisher: 丸善
  • ISBN: 9784621302477