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ResercherID: Y. Hatsugai

Gordon Research Conference

Advances in Topological Phases of Matter in Crystalline Solids and Cold Atom Systems


June 28 - July 3, 2015


The Hong Kong University of Science and Technology
Hong Kong, China

T. Kariyado and Y. Hatsugai
Topological Transition in "Mechanical" Graphene: Chern Number and Edge States
Topological properties of a spring-mass model on the honeycomb lattice, "mechanical graphene", are investigated focusing on Dirac cones in the frequency spectrum. The frequency spectrum is dramatically changed by just modifying tension of springs at equilibrium. We observe creation, migration, and annihilation of Dirac cones as a function of tension at equilibrium. When the time reversal symmetry is broken by uniform rotation of the whole system, the Dirac cones acquire a finite gap, and the system becomes topologically nontrivial. Then, creation and annihilation of Dirac cones observed in the time reversal invariant case appear as a change in the Chern number and propagation direction of the chiral edge modes. We also discuss the importance of the boundary condition to see edge states, in connection to the symmetry protection of the topological states.
[P] The 16th International Conference on the Science and Application of Nanotubes (NT15), Nagoya, June 29-July3 (2015)
[P] Graphene Week 2015, Manchester, UK, June 22-26 (2015)

今年もやります。まずは量子力学3. 冬は 統計力学2. 平成30年の新年あけましておめでとうございます。今年もあと289日!
投稿者 : hatsugai 投稿日時: 2017-12-26 01:33:43 (220 ヒット)

最近の研究成果トピックスとして2017年度の科研費ニュース vol.3 にトポロジカル相とバルク・エッジ対応の関係の解説を我々の研究の背景として書きました。予備知識は不要ですのでご興味のある方はご覧下さい。「トポロジカル物質におけるバルク・エッジ対応」

投稿者 : hatsugai 投稿日時: 2017-12-22 19:52:51 (203 ヒット)

Michel Fruchart (Instituut-Lorentz Universiteit, Leiden) will give a talk on Jan.9 (2018), 10:30 am at Rm. B602 by the title Topology of effective evolutions: oriented scattering networks and the phase rotation symmetry

投稿者 : hatsugai 投稿日時: 2017-12-22 11:33:02 (198 ヒット)

Christopher Mudry (Paul Scherrer Institute, Switzerland) gives a talk by the title "Abelian topological order in three-dimensional space" at Rm. B602 from 14:00 on Dec.28, (2017). The detail is here

投稿者 : hatsugai 投稿日時: 2017-11-27 18:03:29 (460 ヒット)

We are organizing an "International workshop : Variety and universality of bulk-edge correspondence 2018 (BEC2018) . Please do not confuse with Bose-Einstein condensation :) Its program is ready.

投稿者 : hatsugai 投稿日時: 2017-10-06 16:36:02 (261 ヒット)

The entanglement Chern numbers is a Chern number of an entanglement Hamiltonian which characterizes topological properties of a topological phase. Starting from a pure state density matrix of the ground state, one may obtain finite temperature (mixed state) density matrix by tracing out parts of the system. If the entanglement hamiltonian has a finite energy gap, the Chern number is well defined by lowering the temperature. We apply the concept for the 3D topological phases.The parity of the number of the Weyl point gives a well defined topological number to distinguish the the state is topologically non trivial. Have a look at arXiv 1708.03722 . The paper has been accepted for publication in Physical Review B.

    [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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