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初貝 安弘 ORCID iD icon
物理学専攻 教授
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ResercherID: Y.Hatsugai
科研費データベース 初貝安弘
[1]基盤研究S : トポロジカル相でのバルク・エッジ対応の多様性と普遍性:固体物理を越えて分野横断へ
205,140千円 (直接経費 : 157,800千円、間接経費 : 47,340千円)
May 31, 2017 - March 31, 2017
2017年度 : 45,370千円 (直接経費 : 34,900千円、間接経費 : 10,470千円)
Project leader :
初貝 安弘 (筑波大学)
Core Member (alphabetical) : 分担者
青木 秀夫 (東京大学)
福井 隆裕(茨城大学)
岩本 敏 (東京大学)
河原林 透 (東邦大学)
木村 昭夫(広島大学)
高橋 義朗(京都大学)
Adjunct Member (alphabetical): 連携研究者
古田 幹雄 (東京大学)
井村 健一郎 (広島大学)
苅宿 俊風 (物質材料機構)
小林 淳 (京都大学)
中島 秀太 (京都大学)


[1] 科学研究費補助金 挑戦的萌芽研究: 四元数のトポロジカル相での意義の解明への挑戦:多体問題と時間反転の破れ
April 2016 - March 2019
Project leader : Y. Hatsugai
[2] 科学研究費補助金 新学術領域研究(研究領域提案型) 原子層科学
[Web] # 25107005
Project No.: 2506,
Fiscal Years: 2013.4-2018.3
領域代表 齋藤 理一郎(東北大学教授)、理論班 連携研究者 初貝安弘 (筑波大学教授)
Fiscal Years: 2013.4-2018.3
[3]基盤研究A トポロジカル相におけるバルク・エッジ対応の物理とその普遍性:固体物理から冷却原子まで
研究課題番号:26247064 Grant-in-Aid for Scientific Research (A)
April 2014 - March 2017
41,470千円 (直接経費 : 31,900千円、間接経費 : 9,570千円)
Project leader :
初貝 安弘 (筑波大学)
Core Member (alphabetical) : 分担者
青木 秀夫 (東京大学)
福井 隆裕(茨城大学)
河原林 透 (東邦大学)
木村 昭夫(広島大学)
高橋 義朗(京都大学)
Adjunct Member (alphabetical): 連携研究者
井村 健一郎 (広島大学)
苅宿 俊風 (筑波大学)
丸山 勲 (福岡工業大学)
岡 隆史 (東京大学)
[4] 科学研究費補助金 基盤研究B:幾何学的位相による物質相:量子液体及びグラフェンでの応用と展開[Web]
April 2011 - March 2014: 1976万円
# 23340112
Project leader :
初貝 安弘 (筑波大学教授)
Member :
青木 秀夫 (東京大学教授)
河原林 透 (東邦大学教授)
島野 亮 (東京大学准教授)
岡 隆史 (連携研究者:東京大学)
苅宿 俊風 (連携研究者:筑波大学)
丸山 勲 (連携研究者:福岡工業大学)
[5] 科学研究費補助金 基盤研究B:対称性の破れを伴わない量子液体相:幾何学的位相による理論とその応用
April 2008 - March 2011
Project leader : Y. Hatsugai
[6] 科学研究費補助金 特定領域:フラストレーションが創る新しい物性
# 22014002
April 2008 - March 2012
公募研究研究代表者 初貝安弘
project Web site [Web]
[7] 科学研究費補助金 特定領域:スーパークリーン物質で実現する新しい量子相の物理
April 2006 - March 2010
project Web site [Web]
[8] 科学研究費補助金 萌芽研究:量子液体におけるバルクーエッジ対応とエンタングルメントエントロピー
April 2008 - March 2010
Project leader : Y. Hatsugai
[9] 科学研究費補助金 挑戦的萌芽研究:クラマース多重項による四元数的ベリー接続の理論と物理的応用への挑戦
April 2011 - March 2013
Project leader : Y. Hatsugai
# 23540460
[10] 科学研究費補助金 基盤研究C 磁場中の電子状態計算と位相不変量による電子物性
# 23540460
April 2011 - March 2014
研究代表者 物質・材料研究機構 新井正夫、研究分担者 初貝安弘
[11]科学研究費補助金 挑戦的萌芽研究:マヨラナ表示による幾何学的位相とトポロジカル秩序変数
# 25610101
April 2013 - March 2015
II. 大学公式ページ
III-p. 過去の研究費と進行中のプロジェクト (2018)

今年もやります。まずは量子力学3(遠隔). 冬は 統計力学2 改め物性理論II (大学院「ベリー接続の理論とバルクエッジ対応」). 令和二年の新年あけましておめでとうございます。今年もあと63日!
投稿者 : hatsugai 投稿日時: 2020-10-28 10:28:43 (150 ヒット)

The Dirac cone is a typical singular energy dispersion in two dimensions that is a source of various non-trivial topological effects. When realized in real/synthetic materials, it is generically tilted and the equi-energy surface (curve) can be elliptic/hyperbolic (type I/II). The type III Dirac cone is a critical situation between the type I and II that potentially causes various non-trivial physics. As for realization of the type III Dirac cones, we are proposing a generic theoretical scheme without any fine tuning of material parameters . It may also help to synthesize in meta materials. The molecular orbital (MO) construction of the generic flat bands which we are also proposing plays a crutial role. Have a look at "Type-III Dirac Cones from Degenerate Directionally Flat Bands: Viewpoint from Molecular-Orbital Representation" by Tomonari Mizoguchi and Yasuhiro Hatsugai, J. Phys. Soc. Jpn. 89, 103704 (2020) Also arXiv:2007.14643. The paper has been selected as an Editors' choice of J. Phys. Soc. Jpn. (Sep. 2020). See also "News and comments" by Prof. N. Nagaosa.

投稿者 : hatsugai 投稿日時: 2020-10-01 16:07:56 (187 ヒット)

Motivated by a historical example, the Dirac Hamiltonian as a square-root of the Klein-Gordon Hamiltonian, its lattice analogue has been discussed recently. Zero energy states are shared by the parent and its descendant. The story is more than that. Not necessarily zero energy but its high energy part can also share topological characters. We hereby propose a “square-root higher order topological insulator (square-root HOTI)” when its squared parent is HOTI. Based on the simple observation that square of the decorated honeycomb lattice is given by a decoupled sum of the Kagome and honeycomb lattices, we have demonstrate that the “corner states” of the breezing Kagome lattice with boundaries share topological characters with its descendant as the decorated honeycomb lattice. Have a look at our recent paper just published online, "Square-root higher-order topological insulator on a decorated honeycomb lattice" by Tomonari Mizoguchi, Yoshihito Kuno, and Yasuhiro Hatsugai, Phys. Rev. A 102, 033527 (2020), also arXiv:2004.03235.

投稿者 : hatsugai 投稿日時: 2020-09-17 11:42:01 (104 ヒット)

As for a topological characterization of a full Liouvillian (including jump term) for the non hermitian fractional quantum Hall states, we are proposing a pseudospin Chern number associated with the Niu-Thouless-Wu type twists in the doubled Hilbert space. Numerical demonstration of the proposal is explicitely given and its validity is discussed. Have a look at "Fate of fractional quantum Hall states in open quantum systems: Characterization of correlated topological states for the full Liouvillian" by Tsuneya Yoshida, Koji Kudo, Hosho Katsura, and Yasuhiro Hatsugai, Phys. Rev. Research 2, 033428 (2020) (open access).

投稿者 : hatsugai 投稿日時: 2020-08-16 14:53:28 (264 ヒット)

Adiabatic deformation of gapped systems is a conceptual basis of topological phases. It implies that topological invariants of the bulk described by the Berry connection work as topological order parameters of the phase. This is independent of the well-established symmetry breaking scenario of the phase characterization. Adiabatic heuristic argument for the fractional quantum Hall states is one of the oldest such trials that states the "FRACTIONAL" state is deformed to the “INTEGER”. Although it is intuitive and physically quite natural, there exist several difficulties. How the states with different degeneracy are deformed each other adiabatically? We have clarified the questions and demonstrated this adiabatic deformation on a torus in the paper "Adiabatic heuristic principle on a torus and generalized Streda formula" by Koji Kudo and Yasuhiro Hatsugai , Phys. Rev. B 102, 125108 (2020) (also arXiv:2004.00859) What is deformed continuously is a gap not the states ! This is also sufficient for the topological stability of the Chern number (of the degenerate multiplet) as a topological order parameter. Have a look at.

投稿者 : hatsugai 投稿日時: 2020-07-30 12:47:16 (249 ヒット)

Our article on non-hermitian band touching for strongly correlated systems has been published in PTEP (Progress of Theoretical and Experimental Physics), "Exceptional band touching for strongly correlated systems in equilibrium", by Tsuneya Yoshida, Robert Peters, Norio Kawakami, Yasuhiro Hatsugai. Focusing on the non-hermitian topological phenomena for the equilibrium Green function of correlated electrons, a compact review of the exceptonal band touching that is intrinsic for non-hermitian matrices is described as well. Have a look at.

    [0] バルクとエッジ
    [1] 集中講義
    [2] 原論文と解説
    [3] トポロジカル秩序とベリー接続:日本物理学会誌 「解説」 [JPS-HP] [pdf]
    [4] "Band gap, dangling bond and spin : a physicist's viewpoint" [pdf] [Web]
    科研費 1992年度:電子系スピン系におけるトポロジカル効果
    科研費 1994年度:物性論におけるトポロジーと幾何学的位相
    [1] MIT, Boston (2003)
    [2] APS/JPS March Meeting (2004)
    [3] JPS Fall meeting, JAPAN (2004)
    [4] APS/JPS March meeting (2005)
    [5] JPS Fall meeting (2005):Entanglement
    [6] Superclean workshop, Nasu (2006)
    [7] MPIPKS, Dresden (2006)
    [8] KEK, Tsukuba (2007)
    [9] ETH, Zurich (2008)
    [10] ICREA, Sant Benet (2009)
    [11] JPS Meeting, Kumamoto (2009)
    [12]HMF19, Fukuoka (2010)
    [13] NTU, Singapore (2011)
    [14] ICTP, Trieste (2011)
    [15] Villa conf., Orland (2012)
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