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初貝 安弘 ORCID iD icon
筑波大学
筑波大学大学院
数理物質科学研究科
物理学専攻 教授
新HP(試行/作成中)
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ResercherID: Y.Hatsugai
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メインメニュー
「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」
科研費基盤研究A (26247064) 第4回研究会 
平成27年3月25日(金)〜3月26日(土)筑波大学総合研究棟B107,108講義室(ポスター)

プログラム
第1日目:平成28年3月25日(金)
13:00-13:10 初貝 安弘 (筑波大学)
「はじめに。」
13:10-13:55 青木 秀夫(東京大学)
「3次元グラフェン ― helicoidal and zeolitic」
13:55-14:40 高橋 義朗(京都大学)
「冷却原子系のトピックス」
14:40-15:20 ポスターと意見交換
15:20-16:05 木村 昭夫(広島大学)
「「Weyl半金属相のバルクエッジ対応と今後の研究」
16:05-16:45 井村 健一郎(広島大学)
「「トポロジカル絶縁体のZ2性再考」
16:45-17:25 中島 秀太(京都大学)
「「冷却原子系でのcharge pump」
第2日目:平成28年3月26日(土)
8:30-9:15初貝 安弘(筑波大学)
「エッジ状態からみたcharge pump」 [keynote file with movie]
9:15-10:00 福井 隆裕(茨城大学)
「エンタングルメント・チャーン数を中心としたこれまでの研究のまとめ」
10:00-10:40 ポスターと意見交換
10:40-11:25 河原林 透(東邦大学)
「格子模型における一般化されたカイラル対称性を保存する連続変形とその応用」
11:25-11:55 苅宿 俊風(筑波大学)
「古典系における幾何学的位相とバルク・エッジ対応」
11:55-12:00 初貝 安弘(筑波大学)
「おわりに」
ポスター (会場:B108)
1.澤田 あずさ(京都大学)
「charge pumpについて」

2.丸山 勲(福岡工業大学)
「エンタングルメント保存のための光格子系のレーザー配置」
3.吉川 智己(広島大学)
「トポロジカル絶縁体Bi2Te3における 表面光起電力効果とディラック電子ダイナミクス」
4.工藤 耕司(筑波大学)
「Electron-electron interaction and Chern number of two-dimensional electrons
 in a magnetic field」
5.大野 修平(筑波大学)
「Time evolution of edge modes in  photonic crystals」
6.高橋 雄太(筑波大学)
「Peculiar dispersion and edge states of mechanical graphene」
7.荒木 広夢(筑波大学)
「Entanglement Chern Number of the Kane-Mele models with ferromagnetism」
8.板垣 諒(東邦大学)
「高次vortexに伴う非整数電荷のトポロジカルな安定性」
9.吉村 幸徳(広島大学)
「トポロジカル絶縁体ナノワイヤー系におけるスピンベリー曲率と表面状態の局在長の振る舞い」
カテゴリートップ
Talk files (partly password protected)
次
科研費基盤S第1回スタートアップ研究会 June 25 2017

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現在の時刻
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33日!
最新ニュース
投稿者 : hatsugai 投稿日時: 2020-11-03 10:00:50 (97 ヒット)

Thouless' (adiabatic) pump in one-dimension is a typical topological phenomena characterized by the Chern number that correspondes to the quantized motion of the center of mass (COM). Although the COM is only well-defined with boudary (to set the origin of the coordinate), the COM experimentally observed is given by the bulk and the edge states do not contribute. Ultimate adiabaticity, that has never been achieved experimentaly, supports the quantization of the COM supplemented by the periodicity of the system with boundaries. This is the unique bulk-edge correspondence of the pump. We here propose a generic construction using a phase boundary line of the symmetry protect phase with two parameters works as a topological obstruction of the pump in extended parameter space. The construction is purely of manybody and the interaction can be one of the parameters. Have a look at "Interaction-induced topological charge pump" by Yoshihito Kuno and Yasuhiro Hatsugai, Phys. Rev. Research 2, 042024(R), (2020) (Open access)


投稿者 : hatsugai 投稿日時: 2020-10-28 10:28:43 (245 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 (297 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 (171 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 (350 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.


    検索
    バルク・エッジ対応
    [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]
    トポロジカル相
    [0]昔の科研費
    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
    私の講演ファイルのいくつか
    [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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