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初貝 安弘
筑波大学
理工学群副学群長
数理物質系物理学域
筑波大学大学院
数理物質科学研究科
物理学専攻 教授
学際物質科学研究センター(TIMS)教授
初貝写真
Yasuhiro2-Nov11-09
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投稿者 : hatsugai 投稿日時: 2016-05-12 09:29:05 (2458 ヒット)

We are organizing a workshop on the bulk-edge correspondence in relation to cold atoms and ARPES ( theories as well) as a YITP workshop ( Yukawa Institute of theoretical physics) in Kyoto Sep.27-30, 2016. Its registration will be open soon. Stay tuned. [YITP site] . [Direct link].


投稿者 : hatsugai 投稿日時: 2016-01-16 17:16:48 (1176 ヒット)

Topological pump, proposal by Thouless and just recently realized experimeatally in Kyoto and Munich independently, is revisited from the bulk-edge correspondence (BEC). It's typically described by well known Harper equation as in QHE but the view point of BEC supplies quite different physical / mathematical structure. Pumped charge is carried by bulk but its quantization is guaranteed by the topological number defined by a singular motion of the center of mass caused by edge states. However this singular motion can not be observed in reality by a pumping of finite speed.The edge states are hidden! Counting the topological number by singularities of the spectral flow is a standard technique in the discussion of the Atiyah-Patodii-Singer index theorem. The same counting appears in the BEC in the pumping. It's a unexpected surprise. Have a look at arXiv:1601.03537, Phys. Rev. B94, 041102(R) (2016)


投稿者 : hatsugai 投稿日時: 2016-01-16 17:16:20 (813 ヒット)

Our paper is now online. Topology is not only for quantum world. Localised modes near the system boundaries also exist in a classical system that is predicted by bulk. This is the bulk-edge correspondence originally discussed in quantum systems such as quantum (spin) Hall states and graphene. Still this idea is valid in classical world. We discussed topological phenomena in mechanics for point particles connected with springs in a honeycomb shape. Also topological phase transitions associated with its tension is clearly demonstrated as a time evolution of the localized modes. [arXiv:1505.06679]


投稿者 : hatsugai 投稿日時: 2015-09-14 19:50:18 (1187 ヒット)

We are organizing an international workshop on the bulk-edge correspondence / topological phases  Sep. 27-29 (2015) in Tokyo (Myogadani) supported by KAKENHI (JSPS research funding). Tentative program is ready and on the net.


投稿者 : hatsugai 投稿日時: 2015-09-14 19:44:26 (766 ヒット)

Looking at the Landau-Lifshitz again for mechanics, a simple classical system is redescribed topologically. Hannay angle as a classical correspondent of the Berry phase is discussed in relation to the symmetry protection and the bulk-edge correspondence. (arxiv:1508.06946)


投稿者 : hatsugai 投稿日時: 2015-06-18 11:46:16 (701 ヒット)

Our paper "Topological Order Parameters of the Spin-1/2 Dimerized Heisenberg Ladder in Magnetic Field" is published in Phys. Rev.B . [arXiv:1412.7901] . Fractinal quantization of the Berry phase as pi/4 is quite useful for  characterization of some spin ladder with magnetic field.


投稿者 : hatsugai 投稿日時: 2015-06-07 05:55:51 (752 ヒット)

千葉大の中山隆史先生ご紹介にて「バルクエッジ対応の物理の多様性と普遍性」として平成27年7月8日-9日に集中講義をやります。


投稿者 : hatsugai 投稿日時: 2015-03-25 05:33:11 (649 ヒット)

チャーン数に関する私たちの論文 "Chern Numbers in Discretized Brillouin Zone: Efficient Method of Computing (Spin) Hall Conductances" ( T. Fukui, Y. Hatsugai, H. Suzuki ) が第20回(2015年)日本物理学会論文賞に選ばれました。ありがとうございました。


投稿者 : hatsugai 投稿日時: 2015-03-09 11:42:24 (722 ヒット)

The paper "Disentangled topological numbers by a purification of entangled mixed states for non-interacting fermion systems" by Takahiro Fukui and YH is now published in J. Phys. Soc. Jpn. 74, 1674 (2015), also on the net arXiv:1501.07031


投稿者 : hatsugai 投稿日時: 2015-02-25 10:54:05 (994 ヒット)

Flat bands in Weaire-Thorpe model and silicene is discussed and the paper is now published in New J. Phys. as a special issue article for silicene.. Electronic structure of silicene is algebraically described which is qualitatively consistent with the first principle results. Silicene is not a simple generalization of graphene but is featured by the multi-orbital character. Generic arguments for the flat band we have proposed before is nicely applied. [arXiv:1410.7885]


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最新ニュース
投稿者 : hatsugai 投稿日時: 2017-12-26 01:33:43 (70 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 (49 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 (47 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 (220 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 (135 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.


    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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