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ResercherID: Y. Hatsugai
投稿者 : hatsugai 投稿日時: 2016-12-28 12:07:44 (299 ヒット)

We have extended the chiral symmetry to the case with tiled Dirac fermions on lattice. The paper is published in Phys. Rev. B 94, 235307 (2016)

投稿者 : hatsugai 投稿日時: 2016-12-12 13:50:23 (256 ヒット)

Koji Kudo got a poster prize at the workshop in Kobe 2016. Congratulation !

投稿者 : hatsugai 投稿日時: 2016-12-07 09:59:47 (265 ヒット)

日本物理学会 会誌 12月号(2016)の学界ニュースに2016年のノーベル物理学賞(トポロジカル相転移とトポロジカルな物質相)の解説を書きました。 [日本物理学会 会誌最新号目次] 日本物理学会会員の方はマイページよりご覧ください。

投稿者 : hatsugai 投稿日時: 2016-12-01 17:22:36 (251 ヒット)

雑誌 パリティに2016年のノーベル物理学賞についての解説の依頼原稿を書きました。  パリティ(丸善):2016年ノーベル物理学賞:物質をトポロジカルにみる

投稿者 : hatsugai 投稿日時: 2016-12-01 16:41:58 (297 ヒット)

1 千葉市科学館 平成 28 年度 「大人が楽しむ科学教室 ~量子力学シリーズ~」12月4日(日)(4)「トポロジカル物質の母としてのグラフェン」

2 千葉市科学館 平成 28 年度 「大人が楽しむ科学教室 ~量子力学シリーズ~」12月17日(土)(7)「物理学における対称性の役割とトポロジカル相」

投稿者 : hatsugai 投稿日時: 2016-09-16 10:55:24 (501 ヒット)

Our paper on a photonic system in 3D which has the Weyl points due to breaking inversion is published in Phys. Rev. B as an edtors' suggestsion. See also highlights. The Weyl points are characterized as the topopoligical critial points of the sliced 2D system which has a non trivial Chern number (section Chern number) with jumps. Momentum selective edge states propagating near the boundaries are discussed as a typical example of the bulk-edge correspondence. Have a look at !

投稿者 : hatsugai 投稿日時: 2016-05-12 09:29:05 (2420 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 (803 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 (781 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 (1169 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.

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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39日!
投稿者 : hatsugai 投稿日時: 2017-10-06 16:36:02 (82 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 (306 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 (351 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 (274 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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