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Who am I ?
Yasuhiro Hatsugai
ex-Dean of College of Physics (until 2012.3.31)
Professor of Physics
Division of Physics
Faculty of Pure and Applied Sciences
TIMS Member
University of Tsukuba
1-1-1 Tennodai, Tsukuba
Ibaraki 305-8571 JAPAN
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Yasuhiro2-Nov11-09
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HATSUGAI   Lab.     Institute of Physics, University of Tsukuba


L: Topological stability of Dirac cones, merging & C: fractal in graphene (Flying Butterfly) & R: Non Abelian gauge structure in solids
Refereneces :
[1] Y. Hatsugai, T. Fukui, H. Aoki, Phys. Rev. B 74, 205414 (2006) : [Journal Link] , arXiv:cond-mat/0607669
"Topological analysis of the quantum Hall effect in graphene"
[2] Y. Hatsugai, J. Phys. Soc. Jpn. 73, 2604 (2004) : [Journal Link] , arXiv:cond-mat/0405551
"Explicit Gauge Fixing for Degenerate Multiplets: A Generic Setup for Topological Orders"

Hatsugai Group, Condensed Matter Theory

Targets of our research is to explore new insight and find novel physical principles in condensed matter materials and phenomena. We have been working on the following topics. [paper]

[1] Geometrical phases of condensed matter physics
Target material and phenomena
(1) Graphene as a relativistic Dirac particle in solid states
(2) Quantum Hall effects as typical topological insulators
(3) Quantum spin Hall phase as a time reversal invariant topological insulator
(4) Electrons with strong correlation as non trivial quantum liquids
(5) Exotic superconductivity with anisotropic pairing
(6) Frustrated magnets as typical spin liquids
(7) Semiconductor nano-structures as a playground of novel quantum phenomena
(8) Universal edge states in quantum (spin) Hall effects, Haldane magnets, photonic crystals and cold atoms
(9) Aharonov-Bohm effect and its generalization

Theoretical methods and concepts
(1) Non-Abelian gauge structures of the Berry connections
(2) Berry connections and their generalization
(3) Quantum order parameters by the Chern numbers and generic Berry phases
(4) Theory of generic Aharnov-Bohm effects
(5) Entanglement entropy of quantum liquids and spin liquids
(6) Universality of the Bulk-Edge correspondence
(7) Characterization of topological orders in quantum liquids


[2] Novel quantum phenomena in real material and their relation to the emerging mathematical concepts as quantum group
Some works [Link1][Link2]
[3] Novel techniques to study ferimonic many body systems with strong correlation
Basic work [Link]
[4] Realistic electronic structures & topological quantities
One of my basic works [Link]


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  • Graduate courses at Univ. of Tsukuba [Web]
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Institute of Physics
University of Tsukuba
1-1-1 Tennodai
Tsukuba
Ibaraki 305-8571
JAPAN


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Year 2013
A HAPPY NEW YEAR 2014, 39 days left this year !
Recent News
Poster : hatsugai on 2014-08-19 13:29:55 (98 reads)

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]


Poster : hatsugai on 2014-08-06 13:13:14 (239 reads)

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]


Poster : hatsugai on 2014-07-08 18:35:51 (395 reads)

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.


    Search
    Bulk-edge correspondence
    [0] バルクとエッジ
    [1] Focus lecture
    [2] Original papers
    [3] Japanese Physical Society monthly issue Commentary (Only Japanese except abstract) [pdf]
    [4] "Band gap, dangling bond and spin : a physicist's viewpoint" [pdf]
    Topological phases
    [0]Historical project
    KAKEN-HI DB FY1992 : Topological effects in electronic/spin systems
    KAKEN-HI DB FY1994 : Topology & geometrical phases in condensed matter physics
    Some of my talk files
    [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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