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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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Institute of Physics
University of Tsukuba
1-1-1 Tennodai
Tsukuba
Ibaraki 305-8571
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Recent News
Poster : hatsugai on 2018-08-02 10:41:19 (152 reads)

I will give a talk in two coming conferences about topological phases and mathematics.

Progress in the Mathematics of Topological States of Matter, Sendai, AIMR, Tohoku Univ., 13–17 August 2018
Recent progress in mathematics of topological insulators, ETH Zürich, 3rd-6th September 2018


Poster : hatsugai on 2018-07-31 07:27:44 (119 reads)

New topological number as an entanglement polarization for the topological quadrupole phases is defined and its validity is demonstrated, T. Fukui and Y, Hatsugai, Phys. Rev. B 98, 035147, (2018) . It picks up dipolar components of quadrupole phases which are canceled out in total.


Poster : hatsugai on 2018-07-25 13:53:14 (135 reads)

I gave a series of lectures at Kyushu Univ. on the topological phases for grad. students. The detail is here [Link] . Have a look at.


Poster : hatsugai on 2018-06-20 11:30:51 (179 reads)

Our paper on ZN Berry phases for symmetry protected phase (SPT) has been published in Physical Review Letters, T. Kariyado, T. Morimoto and Y. Hatsugai, "ZN Berry phases in SPT phases". Have a look at. Also see EPL in 2011 for the ZN quantization.


Poster : hatsugai on 2018-06-09 07:26:18 (154 reads)

Zongping Gong (Univ. of Tokyo) will talk on the topological phases of non-hermite system on July 11 (2018) (We have updated the typo (date and time) in the poster). It starts from 15:00. Join us.


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    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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