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ResercherID: Y. Hatsugai

[F]  Seminar at M. Ueda Group, Univ. Tokyo, JAPAN, Jan 24 (2013)

PM1:00, Rm. 933, buld. 9, Univ. Tokyo

Title:Symmetry and order parameters for topological phases

Beyond the great success of the Ginzburg-Landau theory associated with symmetry breaking (SB), condensed matter physicists focus on more than that recently. That is, phases without any fundamental SB but possessing characteristic feature are of the central interest, which are the quantum/spin liquids. This class of matter includes quite wide varieties such as quantum (spin) Hall states, gapped quantum spins, anisotropic superfluids/superconductors and graphene. Some of cold atoms and photonic systems belong to the class as well.
Even though the SB is absent, too much generic states are boring. Then still the symmetry plays an important role to constrain the physical states. Gauge symmetries, time-reversal and charge conjugation are important examples. When the quantum/spin liquid is stable against for some perturbation due to geometrical constraints, one may consider the state topological.
As for the topological phases with some symmetry protection, we can define "topological order parameter" using topological objects, such as gap nodes, quantized Berry phases and Chern numbers. Some of edge states, which are induced by geometric perturbation such as boundaries and impurities, are again topologically stable and used for the topological order parameters. This is the bulk-edge correspondence. As for the gapped cases, these topological order parameters are adiabatic invariants and useful for identification of the quantum phase transition.
We will describe generic idea of the topological phases and show validity of our topological characterization for various quantum phases.


[P] MANA seminar & lectures at X. Hu Group at NIMS, Tsukuba, JAPAN, March 6 (2013)
[P] 2013 EMN West Meeting on Topological Insulators, Houston, USA Jan 7-10(2013

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164日!
投稿者 : hatsugai 投稿日時: 2018-06-20 11:30:51 (93 ヒット)

Our paper on ZN Berry phases for symmetry protected phase (SPT) has been published in Physical Review Letters, T. Kariyado, T. Morimoto and Y. Hatsugai, "ZN Berry phases in SPT phases". Have a look at. Also see EPL in 2011 for the ZN quantization.

投稿者 : hatsugai 投稿日時: 2018-06-09 07:26:18 (85 ヒット)

Zongping Gong (Univ. of Tokyo) will talk on the topological phases of non-hermite system on July 11 (2018) (We have updated the typo (date and time) in the poster). It starts from 15:00. Join us.

投稿者 : hatsugai 投稿日時: 2018-06-06 15:25:13 (66 ヒット)

On June 13 (2018), Nobuyuki Yoshioka (Univ. of Tokyo) will give a talk on the physical application of the machine learning "Machine Learning Disordered Topological Phases by Statistical Recovery of Symmetry". Join us.

投稿者 : hatsugai 投稿日時: 2018-04-20 18:51:10 (193 ヒット)

ありがとうございました: 平成30年度科学技術分野の文部科学大臣表彰,科学技術賞(研究部門)初貝安弘「トポロジカル相でのバルクエッジ対応の研究」 [PDF]

投稿者 : hatsugai 投稿日時: 2017-12-26 01:33:43 (414 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」

    [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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