Koike, Tatsuhiko



Faculty of Science and Technology, Department of Physics (Yagami)


Assistant Professor/Senior Assistant Professor

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Career 【 Display / hide

  • 1993.04

    Tokyo Institute of Technology, 物理学科, JSPS postdoctoral fellow

  • 1996.04

    Department of Physics, Keio University, 物理学科, 助手

  • 2000.02

    University of Maryland, JSPS postdoctoral fellow

  • 2007.04

    Keio University, Department of Physics, Research Associate

  • 2009.04

    Faculty of Science and Technology, Keio University, Department of Physics, Assistant Professor

Academic Background 【 Display / hide

  • 1991.03

    The University of Tokyo, Faculty of Science, Department of Physics

    University, Graduated

  • 1993.03

    Tokyo Institute of Technology, Graduate School, Division of Science and Engineeri, 物理学

    Graduate School, Completed, Master's course

  • 1996.03

    Tokyo Institute of Technology, Graduate School, Division of Science and Engineeri, 物理学

    Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide

  • 修士(理学), Tokyo Institute of Technology, Coursework, 1993.03

  • 博士(理学), Tokyo Institute of Technology, Coursework, 1996.03


Research Areas 【 Display / hide

  • Theory of informatics (Fundamental Informatics)

  • Particle/Nuclear/Cosmic ray/Astro physics (Elementary Particle/Atomic Nucleus/Cosmic Ray/Space Physics)

  • Atomic/Molecular/Quantum electronics (Atomic/Molecular/Quantum Electronics, Plasma)


Books 【 Display / hide

  • Singularities in Geometry and Topology

    KOIKE TATSUHIKO, European Mathematical Society, 2012

    Scope: 51-69

  • 爆発と凝集

    原隆、古池達彦, 東京大学出版会, 2006.02

Papers 【 Display / hide

  • A general formulation of time-optimal quantum control and optimality of singular protocols

    Wakamura Hiroaki, Koike Tatsuhiko

    NEW JOURNAL OF PHYSICS 22 ( 7 )  2020.07

    ISSN  1367-2630

  • Cohomogeneity-one-string integrability of spacetimes

    Morisawa Y, Hasegawa S, Koike T, Ishihara H

    Classical and Quantum Gravity (Classical and Quantum Gravity)  36 ( 15 )  2019.07

    Joint Work, Except for reviews,  ISSN  02649381

     View Summary

    © 2019 IOP Publishing Ltd. A classical string whose world sheet shares a one-dimensional symmetry with the spacetime is called cohomogeneity-one (C1). We propose C1-string integrability, i.e. integrability of all C1 strings in the spacetime, as a class of hidden symmetry of a spacetime. The C1 string may probe symmetry which is not probed by a particle. We present a simple, systematic procedure for finding constants of motion of a C1 string and examining C1 string integrability of a spacetime. We apply the framework to some physically important spacetimes such as AdS5, AdS5 × S5, and AdS5 × Tp,q. C1 strings and C1-string integrability may be useful for a prior examination of general string integrability of a highly symmetric spacetime since, among the examples above, all C1 string integrable spacetimes are string-integrable, and the previously obtained chaotic string solutions in those or other spacetimes are of class C1.

  • Disturbance by optimal discrimination

    Ryuitiro Kawakubo and Tatsuhiko Koike

    Physical Review A (American Physical Society)  97 ( 3 ) 032102 (5pp) 2018.03

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  24699926

     View Summary

    © 2018 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. We discuss the disturbance by measurements which unambiguously discriminate between given candidate states. We prove that such an optimal measurement necessarily changes distinguishable states indistinguishable when the inconclusive outcome is obtained. The result was previously shown by Chefles [Phys. Lett. A 239, 339 (1998)PYLAAG0375-960110.1016/S0375-9601(98)00064-4] under restrictions on the class of quantum measurements and on the definition of optimality. Our theorems remove these restrictions and are also applicable to infinitely many candidate states. Combining with our previous results, one can obtain concrete mathematical conditions for the resulting states. The method may have a wide variety of applications in contexts other than state discrimination.

  • State protection by quantum control before and after noise processes

    Hiroaki Wakamura, Ryuitiro Kawakubo, and Tatsuhiko Koike

    Physical Review A (American Physical Society)  96 ( 2 ) 022325 (7pp) 2017.08

    Research paper (scientific journal), Joint Work, Accepted

  • 事前事後制御による状態保護

    若村浩明, 川久保龍一郎, 古池達彦

    第36回量子情報技術研究会予稿集 (電子情報通信学会 量子情報技術時限研究専門委員会)     36 - 40 2017.05

    Research paper (research society, symposium materials, etc.), Joint Work

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Presentations 【 Display / hide

  • A generalization of quantum brachistochrone

    Hiroaki Wakamura, Tatsuhiko Koike

    第21回「特異点と時空、および関連する物理」研究会 (秋田市) , 2019.12, Oral Presentation(general), 特異点研究会組織委員会

  • 量子系での時間最適制御の一般論と特異的な制御

    若村浩明, 川久保龍一郎, 古池達彦

    日本物理学会2019年秋季大会 (岐阜大学柳戸キャンパス) , 2019.09, Oral Presentation(general), 日本物理学会

  • Time-optimal unitary evolution and singular control

    Hiroaki Wakamura and Tatsuhiko Koike

    Gordon Research Conference on Quantum control of Light and Matter (Coherent Control of Quantum Systems with Increasing Complexity) (Newport, USA) , 2019.08, Poster (general)

  • Time-optimal unitary evolution and singular control

    Hiroaki Wakamura and Tatsuhiko Koike

    Gordon Research Seminar on Quantum control of Light and Matter (Quantum Control and Its Applications Across Scientific Disciplines) (Newport, USA) , 2019.08, Poster (general)

  • ドリフト場を持つ量子系に対する時間最適制御の特異性

    若村浩明, 川久保龍一郎, 古池達彦

    第40回量子情報技術研究会 (QIT40) (九州大学筑紫キャンパス) , 2019.05, Oral Presentation(general), 電子情報通信学会エレクトロニクスソサエティ量子情報技術時限付専門委員会

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Research Projects of Competitive Funds, etc. 【 Display / hide

  • 時間最適量子制御の基礎理論と特異制御に関する研究


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 古池 達彦, Grant-in-Aid for Scientific Research (C), Principal Investigator

Awards 【 Display / hide

  • Teshima Memorial Doctoral Thesis Award

    KOIKE TATSUHIKO, 1996.03, 手島工業教育資金団, Renormalization group analysis of critical behaviour in gravitational collapse

    Type of Award: Awards of Publisher, Newspaper Company and Foundation


Courses Taught 【 Display / hide











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Memberships in Academic Societies 【 Display / hide

  • 日本物理学会新著紹介小委員会, 


Committee Experiences 【 Display / hide

  • 2007.11

    Committee Member, 日本物理学会新著紹介小委員会