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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
初貝写真
Yasuhiro2-Nov11-09
会議 & 研究会
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ResercherID: Y.Hatsugai
Project
メインメニュー
筑波大学ーKEK連携mini研究会(初貝代表基盤研究B# 20340098共催)
2009年11月27日筑波大学第一エリア自然学系棟B棟1階B119
那須奎一郎(KEK)-初貝安弘(筑波大) co-chair
プログラム [pdf]
広報[ニュース]

Talks & presentations

[1.] 初貝安弘(筑波大学)
はじめに
[2.] 守友浩(筑波大学)
筑波大・KEK連携について
[3.] 村上洋一(物構研・構造物性センター長)
筑波大・KEK連携について
[Mo-Chair ]那須奎一郎(物構研)
グラファイト関連物質について
[Mo-1.] 谷村克己(阪大産研)
フェムト秒光励起によるグラファイトの構造相転移 [pdf]
[Mo-2.] 西岡圭太(物構研)
光誘起グラファイト-ダイヤモンド相転移の初期過程ダイナミクス
[Mo-3.] 大西宏昌(物構研)
Generation and growth of the diaphite domain by visible photon irradiation onto graphite [pdf]
[Mo-4.] 岡田晋(筑波大物理)
グラファイト複合構造体の電子物性
[Af-Chair 1. ]Chair:岡田晋(筑波大物理)
グラフェンとその周囲
[Af-1.] 青木秀夫(東大物理)
グラフェンにおける光誘起ホール効果 & 光学ホール効果と光電ホール効果 [pdf] [ppt]
[Af-2.] 小野寛太(物構研)
数層グラフェンのX線分光 [pdf]
[Af-3.] 河原林透(東邦大理)
グラフェン量子ホール効果におけるランダムネスのレンジと 対称性 [pdf]
[Af-Chair 2. ]Chair:青木秀夫(東大物理)
グラフェンの特異な電子状態
[Af-4.]神田晶申(筑波大物理)
グラフェンにおける超伝導近接効果 [ppt]
[Af-5.] 新井正男(物材機構)
グラフェン・有機伝導体の「ディラック電子」に対する量子ホール効果の数値的研究 [pdf]
[Af-6.] 山本真幸(物材機構MANA)
ナノリボンジャンクションにおける電気伝導 [pdf]
[Af-7.] 佐々木健一(物材機構MANA)
グラフェン端における擬スピン反射の理論とラマン分光 [pptx]
[Af-8.] 初貝安弘(筑波大物理)
グラフェンにおけるバルクエッジ対応 [pdf]
前
[P] 第5回トピカルミーティング「誘電体にひそむランダムネスとフラストレーション」 Osaka, Dec.18-19 (2009)
カテゴリートップ
国際会議、研究会、セミナー
次
[P] EP2DS-18, Kobe, Japan, July 19 - 24 (2009)

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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67日!
最新ニュース
投稿者 : hatsugai 投稿日時: 2020-10-01 16:07:56 (172 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 (94 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: 2020-09-17 11:06:17 (107 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.


投稿者 : hatsugai 投稿日時: 2020-08-16 14:53:28 (255 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 (239 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.


    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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