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ResercherID: Y. Hatsugai
投稿者 : hatsugai 投稿日時: 2012-04-23 14:54:10 (3059 ヒット)

卒論輪講に読んでみましょう。ちょっと難しいかな?1章は格子上のブラウン運動、自由場の議論が自己完結的に書かれてます。最後の節を除いて十分普通の学部生で読めますね。 [detail]

投稿者 : hatsugai 投稿日時: 2011-06-11 15:15:35 (3711 ヒット)

先日東大生協で "Path Integrals in Quantum Mechanics", (Oxford Graduate Texts) J. Zinn-Justin (著)[Amazon]を見つけました。学生諸氏が Path integral の基礎を学ぶのに適切かな(?)と思いますので、  2011年度の卒業研究で研究室配属になった学生さん他の有志のメンバーの方でこの本の 輪講をはじめました。(まだ2回目ですが、今のところ私も皆勤!)[学生セミナー]。1章はとばして2章から。はてさて一体どうなるものやら。。。期待しています。

補足:6月中旬ですが、そろそろ2章は終了できそうでしょうか。経路積分の教科書としては、Feynmman-Hibbs とかSchulmanよりいいのではないでしょうか。コンパクトにして直接的で正確。

今年もやります。まずは量子力学3. 冬は 統計力学2. 平成31年の新年あけましておめでとうございます。今年もあと79日!
投稿者 : hatsugai 投稿日時: 2019-09-30 11:19:28 (106 ヒット)

Exact flatness of energy bands implies some reasons behind. Here we present one of them, "molecular orbital (MO) representation", which seems to be applied for various classes of tight binding models. Mathematically if the rank of the hamiltonian as a linear operator is less than the number of atomic sites, the kernel of the linear operator has a finite dimension. This is the zero mode flat band. The MO rep. presents nice physical reasons for it. Original proposal by YH with Isao Maruyama in 2011 in EPL and arXiv is counting dimensions of non-orthogonal projections but the hopping of the MO's is allowed as we pointed out (it should be). It's a fun to guess what kinds of the MO representation is possible for a known flat band system. Try ! Also several physical reason why the flat band crosses/touches to dispersive bands in many cases are discussed. Our new paper has appeared in EPL, "Molecular-orbital representation of generic flat-band models", by T. Mizoguchi and Y. Hatsugai , also arXiv.

投稿者 : hatsugai 投稿日時: 2019-09-10 11:03:57 (101 ヒット)

I wrote a small article "So Small Implies So Large: For a Material Design" in the "News and comment" section of the JPSJ in relation to a recent interesting paper by Toshikaze Kariyado. Material deformation induces a gauge field that modifies electronic structure and may result in the Landau levels without breaking time reversal. Have a look at.

投稿者 : hatsugai 投稿日時: 2019-09-09 22:11:58 (107 ヒット)

Our paper "Higher-Order Topological Phase in a Honeycomb-Lattice Model with Anti-Kekulé Distortion" by Tomonari Mizoguchi, Hiromu Araki, and Yasuhiro Hatsugai, has appeared in J. Phys. Soc. Jpn. 88, 104703 (2019). One can access also via arXiv:1906.07928. Z6 quantization in honeycomb structure is the key. Have a look at.

投稿者 : hatsugai 投稿日時: 2019-08-26 14:24:32 (149 ヒット)

Ryo Okugawa (WPI-AIMR, Tohoku Univ.) will be telling us on his recent work as a title "Chiral-symmetry protected second-order topological phases" on Sep. 18 (2019). Rm. D301 from 13:30pm. Join us.

投稿者 : hatsugai 投稿日時: 2019-08-08 00:43:18 (151 ヒット)

Due to an intrinsic symmetry of a mechanical system with friction governed by the Newton equation, exceptional rings appear in two dimensions. We have demonstrated it and classification of symmetry-protected non-Hermitian degeneracies is addressed putting a focus on the symmetry. The paper is published in Physical Review B, "Exceptional rings protected by emergent symmetry for mechanical systems" by Tsuneya Yoshida and Yasuhiro Hatsugai. You may find also here arXiv:1904.10764.

    [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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