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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
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25aSB-2 1549
電場中の2層グラフェンにおけるゼロエネルギーランダウ準位のトポロジカルな安定性
河原林透,初貝安弘A,青木秀夫B
東邦大理,筑波大物理A,東大理B
領域4
25aSB-3 3908
電子間相互作用による磁場下グラフェンの局在状態
濱本雄治,初貝安弘,青木秀夫A
筑波大物理,東大物理A
領域4
26pAG-6 1886
2次元パイロクロア格子におけるクロスダイマー相と量子化ベリー位相
棚谷翔,丸山勲A,初貝安弘
筑波大物理,阪大基礎工A
領域11
26pCJ-8 3410
2次元半導体ナノ構造における多電子波束ダイナミクスの検討
高田幸宏A,塩川太郎B,尹永択B,岩田潤一E,小鍋哲A,F,有川晃弘C,村口正和D,F,遠藤哲郎C,D,F,初貝安弘A,F,白石賢二A,E,F
筑波大院数物A,筑波大物理B,東北大スピントロニクスセC,東北大学際セD,筑波大計算セE,CREST-JSTF
領域4
27pBG-1 1041
Short-range entangled 系におけるZQ量子化ベリー位相の応用
初貝安弘A,丸山勲B
筑波大物理A,阪大基礎工B
領域11
27pBG-8 3615
フェルミオン・ダブリングを伴わないディラック電子のランダウ準位に対するランダムネスの効果
本田貴大,初貝安弘A,青木秀夫B,河原林透
東邦大理,筑波大物理A,東大理B
領域11
27pCE-4 3294
半導体ナノ構造における多電子波束ダイナミクスの印加電圧依存性
塩川太郎A,高田幸宏B,尹永択A,岩田潤一E,小鍋哲B,F,有川晃弘C,村口正和D,F,遠藤哲郎C,D,F,初貝安弘B,F,白石賢二B,E,F
筑波大物理A,筑波大院数物B,東北大スピントロニクス集積化セC,東北大学際セD,筑波大計科セE,CREST-JSTF
領域4

   
前
[P] Villa Conference on Topological Insulators, Orlando USA, April 16th to 20th (2012)
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国際会議、研究会、セミナー
次
[P] KITP Workshop on The Physics of Graphene, KITP Santa Barbara USA, Jan. 3-31 (2012)

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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37日!
最新ニュース
投稿者 : hatsugai 投稿日時: 2020-11-03 10:00:50 (81 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 (218 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 (274 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 (151 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 (333 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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