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ResercherID: Y. Hatsugai
投稿者 : hatsugai 投稿日時: 2015-09-14 19:44:26 (729 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 (681 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 (711 ヒット)


投稿者 : hatsugai 投稿日時: 2015-03-25 05:33:11 (642 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 (711 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 (951 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]

投稿者 : hatsugai 投稿日時: 2015-02-19 00:54:08 (983 ヒット)

Massive/massless Dirac cones with/without tilting for 2D semiconductors are described and now the paper has been published in Phys. Rev.B. 4D notations are used for compact derivations of the Landau levels of Dirac cones, extended chiral symmetry and generalized Aharonov-Casher type shifted zero modes. [arXiv:1410.6250] This is a kind of general description of the narrow gap semiconductor as the gapped Dirac cones with tilting. I am sure it can be useful.

投稿者 : hatsugai 投稿日時: 2014-08-19 13:29:55 (722 ヒット)

Takahiro Fukui and I have put a new paper "Entanglement Chern number for an extensive partition of a topological ground state" on the net. It can be a useful tool for several topological phases where conventional Chern numbers are trivial due to some symmetrical constraints. [arXiv]

投稿者 : hatsugai 投稿日時: 2014-08-06 13:13:14 (993 ヒット)

Our recent paper with Toshikaze Kariyado is accepted for publication in Phys. Rev. B where the bulk-edge correspondence is discussed with the Berry connections and adiabatic continuation. As an example, lattice Dirac fermions with 1/4 filling are described with several types of edges where quantized Berry phases in unit of pi/2 is useful. Have a look at [arXiv:1404.4451]

投稿者 : hatsugai 投稿日時: 2014-07-08 18:35:51 (910 ヒット)

Now our paper is published in Phys. Rev. B. It is also on the net arXiv:1403.1648, "Polarization as a topological quantum number in graphene" with Hideo Aok. In the article, one more topological invariant for the Hofstadter problem and graphene is described. Have a look at.

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今年もやります。まずは量子力学3. 冬は 統計力学2. 平成29年の新年あけましておめでとうございます。今年もあと44日!
投稿者 : hatsugai 投稿日時: 2017-10-06 16:36:02 (65 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.

投稿者 : hatsugai 投稿日時: 2017-08-17 17:01:30 (295 ヒット)

初貝研究室では今回助教2名を公募いたします(公募締め切り2017年9月15日)。委細は [助教公募] をご確認ください。適任者のご推薦、ご応募の方よろしくお願いいたします。

投稿者 : hatsugai 投稿日時: 2017-08-17 17:00:09 (333 ヒット)

We are organizing a Japan-Swiss workshop TTCM2017 at EPOCHAL Tsukuba, Sep.10-13 (2017). Limited number of posters will be still accepted.

投稿者 : hatsugai 投稿日時: 2017-08-03 13:38:17 (256 ヒット)

A numerical scheme to calculate the many body Chern number for a ground state multiplet is formulated and explicitly given for projected bands of any lattice. We demonstrate its validity for lattice analogue of the nu=1/3 and 1/2 states. The string gauge to realize the minimum flux compatible with the periodicity of the unit cell is also presented. [arXiv:1707.06722]. The paper is published in JPSJ lett.

    [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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