Stability and Density fluctuation of superfluids and supersolids in non-uniform Bose-Einstein condensates

• Project/Area Number: 24540361
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: The University of Tokyo
• Principal Investigator: KATO Yusuke 東京大学, 総合文化研究科, 准教授 (20261547)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2014: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2013: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2012: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
• Keywords: 超流動 / 量子渦 / 臨界速度 / 密度揺らぎ / エネルギーランドスケープ / ボース・アインシュタイン凝縮 / 分岐理論 / スワローテール / 擬弧長法 / ソリトン / 動的密度ゆらぎ / 位相欠陥 / ジョセフソン効果 / 安定性 / グロスピタエフスキー方程式 / ボゴリューボフ方程式 / 密度ゆらぎ / サドルノード分岐

Outline of Final Research Achievements

Superfluidity is a macroscopic flow without viscosity and energy dissipation. Superfluid state is stable when the velocity of flow is sufficiently slow. When the velocity exceeds a threshold(which is called critical velocity), the superfluid breaks down accompanied by vortex generation. Physicists try to understand the mechanism of breakdown of superfluidity by making a "map" that tells us how the stable(metastable) and unstable states are connected in the physical space. "The height" in this map corresponds to the energy of each physical state and the map for physicists is called "energy landscape". We have found that the map has more rich structures or connectivity of "valleys" (stable state) and "ridges" than anticipated. Each ridge corresponds to physical state with many pairs of quantum vortices.

Research Products

• [Journal Article] Metastability, excitations, fluctuations, and multiple-swallowtail structures of superfluid of a Bose-Einstein condensate in the presence of a uniformly moving defect (2015)
  • Author(s): Masaya Kunimi and Yusuke Kato
  • Journal Title: Physicall Review A Volume: 91 Pages: 0-0
  • Peer Reviewed
• [Journal Article] 超流動、ボース・アインシュタイン凝縮、密度ゆらぎ (2015)
  • Author(s): 加藤雄介 渡部昌平
  • Journal Title: 日本物理学会会誌 Volume: 70 Pages: 0-0
  • Peer Reviewed
• [Journal Article] Particle Propagator of Spin Calogero-Sutherland Model (2014)
  • Author(s): Ryota Nakai and Yusuke Kato
  • Journal Title: Journal of Physics A Volume: 47 Issue: 30 Pages: 305205-305205
  • DOI: 10.1088/1751-8113/47/30/305205
  • Peer Reviewed
• [Journal Article] Precursor Phenomena of Nucleations of Quantized Vortices in the Presence of a Uniformly Moving Obstacle in Bose-Einstein Condensates (2014)
  • Author(s): Masaya Kunimi and Yusuke Kato
  • Journal Title: J. Low 丁emp. Phys Volume: 175 Issue: 1-2 Pages: 201-207
  • DOI: 10.1007/s10909-013-0964-9
  • Peer Reviewed
• [Journal Article] Stability Criterion for Superfluidity in the light of Density Spectral Function (2013)
  • Author(s): S. Watabe, Y. Kato
  • Journal Title: Phys. Rev. A Volume: 88 Issue: 6 Pages: 63612-63612
  • DOI: 10.1103/physreva.88.063612
  • Peer Reviewed
• [Journal Article] Mean-field and stability analysis of two-dimensional flowing soft-core bosons modeling a supersolid (2012)
  • Author(s): Masaya Kunimi and Yusuke Kato
  • Journal Title: Physical Review B Rapid communications Volume: 89 Issue: 6
  • DOI: 10.1103/physrevb.86.060510
  • Peer Reviewed
• [Journal Article] Excitation Transport through a Domain Wall in a Bose-Einstein Condensate (2012)
  • Author(s): S.Watabe, Y. Kato, Y.Ohashi
  • Journal Title: Phys. Rev. A Volume: 86 Issue: 2
  • DOI: 10.1103/physreva.86.023622
  • Peer Reviewed
• [Journal Article] Anomalous Tunneling of Spin Wave in Polar State of Spin-1 BEC (2012)
  • Author(s): S. Watabe, Y. Kato and Y. Ohashi
  • Journal Title: Journal of Physics: Conference Series Volume: 400 Issue: 1 Pages: 012079-012079
  • DOI: 10.1088/1742-6596/400/1/012079
  • Peer Reviewed
• [Journal Article] Dynamics of one-dimensional supersolids (2012)
  • Author(s): Masaya Kunimi, Michikazu Kobayashi, Yusuke Kato
  • Journal Title: Journal of Physics : Conference Series Volume: 400 Issue: 1 Pages: 1-4
  • DOI: 10.1088/1742-6596/400/1/012037
  • Peer Reviewed
• [Journal Article] Anomalous Tunneling of Spin Wave in Heisenberg Ferromagnet (2012)
  • Author(s): Y. Kato, S. Watabe and Y. Ohashi
  • Journal Title: Journal of Physics: Conference Series Volume: 400 Issue: 3 Pages: 032036-032036
  • DOI: 10.1088/1742-6596/400/3/032036
  • Peer Reviewed
• [Presentation] 不均一ポテンシャル中の超流動 (2015)
  • Author(s): 越田真史 加藤雄介
  • Organizer: 日本物理学会年次大会
  • Place of Presentation: 早稲田大学、東京
  • Year and Date: 2015-03-21
• [Presentation] トーラス中 BEC における多重 swallowtail 構造 (2015)
  • Author(s): 國見昌哉, 加藤雄介
  • Organizer: 日本物理学会年次大会
  • Place of Presentation: 早稲田大学、東京
  • Year and Date: 2015-03-21
• [Presentation] 不均一ポテンシャル中のボース系の超流動 (2014)
  • Author(s): 越田真史 加藤雄介
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 中部大学、春日井市、愛知県
  • Year and Date: 2014-09-08
• [Presentation] Transmission and scattering properties of Nambu-Goldstone (2014)
  • Author(s): Yusuke Kato
  • Organizer: Higgs modes in condensed matter and quantum gases
  • Place of Presentation: 京都大学基礎物理学研究所、京都
  • Year and Date: 2014-06-26
  • Invited
• [Presentation] Superfluidity of a Bose system in a non-uniform potential (2014)
  • Author(s): Shinji Koshida
  • Organizer: Higgs modes in condensed matter and quantum gases
  • Place of Presentation: 京都大学基礎物理学研究所、京都
  • Year and Date: 2014-06-24
• [Presentation] Stability Analysis of two-dimensional Bose-Einstein condensates in the presence of a Gaussian potential (2013)
  • Author(s): M. Kunimi and Y. Kato
  • Organizer: 44th Annual Damop Meeting
  • Place of Presentation: Quebec City Convention Center, Quebec city, Quebec, Canada
• [Presentation] Stability Analysis of two-dimensional Bose-Einstein condensates in the presence of a Gaussian potential (2013)
  • Author(s): M. Kunimi and Y. Kato
  • Organizer: Statphys25
  • Place of Presentation: Seoul National University, Seoul, Korea
• [Presentation] Precursor phenomena of nucleations of quantized vortices in the presence of a uniformly moving obstacle in Bose-Einstein condensates (2013)
  • Author(s): M. Kunimi and Y. Kato
  • Organizer: QFS2013
  • Place of Presentation: くにびきメッセ、松江、島根
• [Presentation] 量子渦生成にともなう超流動崩壊の前駆現象 (2013)
  • Author(s): 國見昌哉、加藤雄介
  • Organizer: 熱場の量子論とその応用
  • Place of Presentation: 京都大学基礎物理学研究所、京都市、京都府
• [Presentation] 量子渦生成にともなう超流動崩壊の前駆現象としての密度ゆらぎ (2013)
  • Author(s): 國見昌哉、加藤雄介
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 徳島大学、徳島市、徳島県
• [Presentation] 空間的に不均一なBose 凝縮体の超流動臨界速度近傍における動的密度揺らぎの解析 (2013)
  • Author(s): 國見昌哉, 加藤雄介
  • Organizer: 日本物理学会第68 回年次大会
  • Place of Presentation: 広島大学（広島県、東広島市）
• [Presentation] Excitation spectrum and stability analysis of a supersolid (2012)
  • Author(s): Masaya Kunimi and Yusuke Kato
  • Organizer: QFS2012
  • Place of Presentation: ランカスター大学(イギリス)
• [Presentation] Josephson effect in two-dimensional supersolids (2012)
  • Author(s): G. Anagama, M. Kunimi and Y. Kato
  • Organizer: QFS2012
  • Place of Presentation: ランカスター大学(イギリス)
• [Presentation] 2 次元超流動固体の超流動流状態の安定性および励起状態の解析 (2012)
  • Author(s): 國見昌哉, 加藤雄介
  • Organizer: 日本物理学会2012秋季大会
  • Place of Presentation: 横浜国立大学(神奈川県、横浜市)
• [Presentation] 超流動の安定性と分岐理論 (2012)
  • Author(s): 加藤雄介
  • Organizer: 基研研究会2012非平衡系の物理
  • Place of Presentation: 京都大学（京都府、京都市）
  • Invited
• [Remarks] 加藤雄介研究室
  • URL: http://park.itc.u-tokyo.ac.jp/kato-yusuke-lab/
• [Remarks] 加藤雄介研究室
  • URL: http://park.itc.u-tokyo.ac.jp/kato-yusuke-lab/