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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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会議 & 研究会
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ResercherID: Y.Hatsugai
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メインメニュー
[1] 格子上の分数等系粒子と組紐群
「シリンダー及びトーラス上の分数量子統計:くみひも群およびゲージ不変性」日本物理学会誌「解説」881, Vol. 47(1992) [直接 pdf]  [日本物理学会誌]
[2] 量子ホール系でのバルクーエッジ対応
「量子ホール効果におけるエッジ状態と位相不変量」固体物理340号(1994) [pdf]
[3] グラフェンのエッジ状態の起源
予備原稿。完全版はグラフェンの機能と応用展望 シーエムシー出版(2009) を参照のこと[pdf]
[4] 新しい秩序相としての量子液体相(非専門家向け)
「物性物理・数学・計算科学の融合」藤原毅夫先生の東大・物工ご退職を記念して 平成19年2月[pdf]
[5] 量子液体のトポロジカルな特徴付け(非専門家向け)
予備原稿。完成版はトポロジーデザイニング-新しい幾何学からはじめる物質・材料設計ー NTS Inc. (2009) [pdf]
[6] フラストレート系でのベリー位相と分数化(非専門家向け)
川村特定「フラストレーションが創る新しい物性」ニュースレター(2009) [pdf]
[7] 非可換ベリー位相
「物理における位相の世界」− 量子現象の幾何学 − 数理科学 2007年6月号 528 [pdf]
[8]フラストレーションが創る新しい物性 平成22年度立ち上げ全体会議アブストラクト
初貝安弘 「フラストレーションとバルク-エッジ対応」 [pdf]
[9]「トポロジカル秩序と幾何学的位相」
初貝安弘 [pdf]
[10]トポロジカル秩序とベリー位相
日本物理学会2013年1月号「解説」[9]を全面改定したものです。[pdf]
[11]グラフェンに関するノーベル物理学賞関連
当時のまとめ [page]
[12]グラフェンでの原子崩壊
「グラフェンで原子崩壊が現実に」初貝安弘(訳)パリティ2013年11月号
キーワード: グラフェン, 原子崩壊
”Graphene yields evidence of atomic collapse”, Ashley G. Smart, physics today (Levitov @ MIT)
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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!
最新ニュース
投稿者 : hatsugai 投稿日時: 2020-10-28 10:28:43 (152 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 (189 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 (105 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 (266 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 (252 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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