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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
科研費基盤研究S (17H06138) 第1回スタートアップ研究会 
平成29年6月25日(日)筑波大学東京キャンパス文京校舎 120講義室(講演),122講義室(ポスター)


午前:セッション1 (座長:福井)
8:30-9:10 初貝 安弘 (筑波大学)
9:10-9:50 木村 昭夫 (広島大学)
9:50-10:30 岩本 敏 (東京大学)

10:30-11:30 ポスター(AM)

午前:セッション2 (座長:河原林)
11:30-11:55 高橋 義朗 (京都大学)
11:55-12:20 小野 滉貴 (京都大学)
「1S0-3P0状態の冷却Yb原子を用いた研究 -トポロジカル物理の量子シミュレーションに向けて-」
12:20-12:45 素川 靖司 (JST・京都大学)

12:45-13:40 昼食

午後:セッション1 (座長:高橋)
13:40-14:10 古田 幹雄 (東京大学)
14:10-14:40 林 晋 (産総研・東北大学オープンイノベーションラボ)
14:40-15:10 井村 健一郎 (広島大学)
15:10-15:40 福井 隆裕 (茨城大学)
「Topological magneto-electric pump in three dimensions」

15:40-16:40 ポスター(PM)

午後:セッション2 (座長:木村)
16:40-17:10 青木 秀夫 (東京大学)
17:10-17:40 河原林 透 (東邦大学)
17:40-18:10 久野 義人 (京都大学)
18:10-18:15 初貝 安弘(筑波大学)

P. 1(AM) 小林 淳 (京都大学)
P. 2(PM) 中島 秀太 (京都大学)
「Topological Thouless pumping of ultracold atoms in optical lattices」
P. 3(AM) 苅宿 俊風 (物質材料機構)
「Band singularity by competition between band inversion and spin-orbit coupling」
P. 4(PM) 高橋 駿 (京都工芸繊維大学)
「Optical Weyl Points below the Light Line in Semiconductor Chiral Woodpile Photonic Crystals」
P. 5(AM) 金 仁基 (東京大学)
「Observation of Topological Interface State of Elastic Wave in 1D Phononic Crystal」
P. 6(PM) 角田 一樹 (広島大学)
P. 7(AM) 吉川 智己 (広島大学)
P. 8(PM) 大野 修平 (筑波大学)
「Photonic band of rotationally-stacked woodpile structure and deformation」
P.9(AM) 工藤 耕司 (筑波大学)
「Projected electron-electron Interaction of Landau-Hofstadter Bands on Several Lattices」
P.10(PM) 吉村 幸徳 (産総研・東北大学)
「Transport properties of disordered topological quantum pumping: from the view point of bulk-edge correspondence」
P.11(AM) 荒木 広夢 (筑波大学)
「Structure of entanglement Hamiltonians for models of 3D topological insulators」
P.12(PM) 平坂 真央 (東邦大学)
P. 13(AM) 藤澤 周平 (東邦大学)
科研費基盤A第4回研究会 March 2016
Talk files (partly password protected)
科研費基盤S第1回スタートアップ研究会 June 25 2017 写真

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!
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 (349 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.

    [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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