Details of the Researcher

PHOTO

Gen Kimura
Section
Graduate School of Information Sciences
Job title
Professor
Degree

Research Interests 10

  • 量子開放系理論

  • 一般確率論

  • 量子情報

  • 量子力学基礎論

  • 量子暗号

  • 量子コンピューティング

  • 量子情報処理

  • open quantum theory

  • foudations of quantum theory

  • quantum information theory

Research Areas 4

  • Natural sciences / Mathematical physics and basic theory /

  • Informatics / Information theory /

  • Natural sciences / Applied mathematics and statistics /

  • Natural sciences / Basic mathematics /

Papers 50

  1. Universal bound on the eigenvalues of 2-positive trace-preserving maps

    Frederik vom Ende, Dariusz Chruściński, Gen Kimura, Paolo Muratore-Ginanneschi

    Linear Algebra and its Applications　2026/02

    DOI： 10.1016/j.laa.2025.10.022 　

    ISSN： 0024-3795

  2. A universal constraint for relaxation rates for quantum Markov generators: complete positivity and beyond*

    Dariusz Chruściński, Frederik vom Ende, Gen Kimura, Paolo Muratore-Ginanneschi

    Reports on Progress in Physics　2025/09/01

    DOI： 10.1088/1361-6633/ae075f 　

    ISSN： 0034-4885 1361-6633

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    <jats:title>Abstract</jats:title> <jats:p>Relaxation rates are key characteristics of quantum processes, as they determine how quickly a quantum system thermalizes, equilibrates, decoheres, and dissipates. While they play a crucial role in theoretical analyses, relaxation rates are also often directly accessible through experimental measurements. Recently, it was shown that for quantum processes governed by Markovian semigroups, the relaxation rates satisfy a universal constraint: the maximal rate is upper-bounded by the sum of all rates divided by the dimension of the Hilbert space. This bound, initially conjectured a few years ago, was only recently proven using classical Lyapunov theory. In this work, we present a new, purely algebraic proof of this constraint. Remarkably, our approach is not only more direct but also allows for a natural generalization beyond completely positive semigroups. We show that complete positivity can be relaxed to two-positivity without affecting the validity of the constraint. This reveals that the bound is more subtle than previously understood: two-positivity is necessary, but even when further relaxed to Schwarz maps, a slightly weaker—yet still non-trivial—universal constraint still holds. Finally, we explore the connection between these bounds and the number of steady states in quantum processes, uncovering a deeper structure underlying their behavior.</jats:p>

  3. Trade-off relations between measurement dependence and hidden information for factorizable hidden variable models Peer-reviewed

    Ryo Takakura, Kei Morisue, Issei Watanabe, Gen Kimura

    Quantum　9　1662-1662　2025/03/14

    Publisher: Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften

    DOI： 10.22331/q-2025-03-14-1662 　

    eISSN： 2521-327X

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    The Bell theorem is explored in terms of a trade-off relation between underlying assumptions within the hidden variable model framework. In this paper, recognizing the incorporation of hidden variables as one of the fundamental assumptions, we propose a measure termed `hidden information&amp;apos; taking account of their distribution. This measure quantifies the number of hidden variables that essentially contribute to the empirical statistics. For factorizable models, hidden variable models that satisfy `locality&amp;apos; without adhering to the measurement independence criterion, we derive novel relaxed Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) inequalities. These inequalities elucidate trade-off relations between measurement dependence and hidden information in the CHSH scenario. It is also revealed that the relation gives a necessary and sufficient condition for the measures to be realized by a factorizable model.

  4. Universal bound on the relaxation rates for quantum Markovian dynamics Peer-reviewed

    Paolo Muratore-Ginanneschi, Gen Kimura, Dariusz Chruściński

    Journal of Physics A: Mathematical and Theoretical　58　(4)　045306-045306　2025/01/24

    Publisher: IOP Publishing

    DOI： 10.1088/1751-8121/adaa3f 　

    ISSN： 1751-8113

    eISSN： 1751-8121

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    Abstract Relaxation rates provide important characteristics both for classical and quantum processes. Essentially they control how fast the system thermalizes, equilibrates, decoheres, and/or dissipates. Moreover, very often they are directly accessible to be measured in the laboratory and hence they define key physical properties of the system. Experimentally measured relaxation rates can be used to test validity of a particular theoretical model. Here we analyze a fundamental question: does quantum mechanics provide any nontrivial constraint for relaxation rates? We prove the conjecture formulated a few years ago that any quantum channel implies that a maximal rate is bounded from above by the sum of all the relaxation rates divided by the dimension of the Hilbert space. It should be stressed that this constraint is universal (it is valid for all quantum systems with finite number of energy levels) and it is tight (cannot be improved). In addition, the constraint plays an analogous role to the seminal Bell inequalities and the well known Leggett–Garg inequalities (sometimes called temporal Bell inequalities). Violations of Bell inequalities rule out local hidden variable models, and violations of Leggett–Garg inequalities rule out macrorealism. Similarly, violations of the relaxation bound rule out Markovian (meaning CP-divisible) evolution.

  5. Uncertainty relations based on a state-dependent norm of a commutator Peer-reviewed

    Aina Mayumi, Gen Kimura, Hiromichi Ohno, Dariusz Chruściński

    Physical Review A　110　(6)　2024/12/16

    Publisher: American Physical Society (APS)

    DOI： 10.1103/physreva.110.062215 　

    ISSN： 2469-9926

    eISSN： 2469-9934

  6. Böttcher-Wenzel inequality for weighted Frobenius norms and its application to quantum physics Peer-reviewed

    Aina Mayumi, Gen Kimura, Hiromichi Ohno, Dariusz Chruściński

    Linear Algebra and its Applications　700　35-49　2024/11

    Publisher: Elsevier BV

    DOI： 10.1016/j.laa.2024.07.013 　

    ISSN： 0024-3795

  7. Universal constraint for relaxation rates of semigroups of qubit Schwarz maps Peer-reviewed

    Dariusz Chruściński, Gen Kimura, Farrukh Mukhamedov

    Journal of Physics A: Mathematical and Theoretical　57　(18)　185302-185302　2024/04/22

    Publisher: IOP Publishing

    DOI： 10.1088/1751-8121/ad3c82 　

    ISSN： 1751-8113

    eISSN： 1751-8121

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    Abstract Unital qubit Schwarz maps interpolate between positive and completely positive maps. It is shown that the relaxation rates of the qubit semigroups of unital maps enjoying the Schwarz property satisfy a universal constraint, which provides a modification of the corresponding constraint known for completely positive semigroups. As an illustration, we consider two paradigmatic qubit semigroups: Pauli dynamical maps and phase-covariant dynamics. This result has two interesting implications: it provides a universal constraint for the spectra of qubit Schwarz maps and gives rise to a necessary condition for a Schwarz qubit map to be Markovian.

  8. Relaxed Bell inequality as a trade-off relation between measurement dependence and hiddenness Peer-reviewed

    Gen Kimura, Yugo Susuki, Kei Morisue

    Physical Review A　108　(2)　2023/08/18

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.108.022214 　

    ISSN： 2469-9926 2469-9934

  9. One-parameter generalization of the Böttcher-Wenzel inequality and its application to open quantum dynamics Peer-reviewed

    Dariusz Chruściński, Gen Kimura, Hiromichi Ohno, Tanmay Singal

    Linear Algebra and its Applications　656　158-166　2023/01

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.laa.2022.09.022 　

    ISSN： 0024-3795

  10. Construction of general symmetric-informationally-complete–positive-operator-valued measures by using a complete orthogonal basis Peer-reviewed

    Masakazu Yoshida, Gen Kimura

    Physical Review A　106　(2)　2022/08/10

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.106.022408 　

    ISSN： 2469-9926 2469-9934

    eISSN： 2469-9934

  11. Bounding the Frobenius norm of a q-deformed commutator Peer-reviewed

    Dariusz Chruściński, Gen Kimura, Hiromichi Ohno, Tanmay Singal

    Linear Algebra and its Applications　646　95-106　2022/08

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.laa.2022.03.021 　

    ISSN： 0024-3795

  12. Constraints for the spectra of generators of quantum dynamical semigroups Peer-reviewed

    Dariusz Chruściński, Ryohei Fujii, Gen Kimura, Hiromichi Ohno

    Linear Algebra and its Applications　630　293-305　2021/12

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.laa.2021.08.012 　

    ISSN： 0024-3795

  13. Universal Constraint for Relaxation Rates for Quantum Dynamical Semigroup Peer-reviewed

    Dariusz Chru{\'{s } }ci{\'{n } }ski, Gen Kimura, Andrzej Kossakowski, Yasuhito Shishido

    Physical Review Letters　127　(5)　2021/07/30

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physrevlett.127.050401 　

  14. Entanglement extracted from vacuum into accelerated Unruh-DeWitt detectors and energy conservation Peer-reviewed

    Jun-ichirou Koga, Kengo Maeda, Gen Kimura

    Physical Review D　100　(6)　2019/09/23

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physrevd.100.065013 　

  15. Quantum teleportation in vacuum using only Unruh-DeWitt detectors Peer-reviewed

    Jun-ichirou Koga, Gen Kimura, Kengo Maeda

    Physical Review A　97　(6)　2018/06/26

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.97.062338 　

  16. Information storing yields a point-asymmetry of state space in general probabilistic theories

    Keiji Matsumoto, Gen Kimura

    2018/02/04

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    The state spaces of both classical and quantum systems have a point-asymmetry about the maximally mixed state except for bit and qubit systems. In this paper, we find an informational origin of this asymmetry: In any operationally valid probabilistic model, the state space has a point-asymmetry in order to store more than a single bit of information. In particular, we introduce a storable information as a natural measure of the storability of information and show the quantitative relation with the so-called Minkowski measure of the state space, which is an affinely invariant measure for point-asymmetry of a convex body. We also show the relation between these quantities and the dimension of the model, inducing some known results in \cite{ref:KNI} and \cite{ref:FMPT} as its corollaries. Also shown are a generalization of weaker form of the dual structure of quantum state spaces, and a generalization of the maximally mixed states as points of the critical set.

  17. Universal Constraints on Relaxation Times for d-Level GKLS Master Equations Peer-reviewed

    Gen Kimura, Shigeru Ajisaka, Kyouhei Watanabe

    Open Systems & Information Dynamics　24　(04)　1740009-1740009　2017/12

    Publisher: World Scientific Pub Co Pte Lt

    DOI： 10.1142/s1230161217400091 　

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    <jats:p> In 1976, Gorini, Kossakowski, Sudarshan and Lindblad independently discovered a general form of master equations for an open quantum Markovian dynamics. In honor of all the authors, the equation is nowadays called the GKLS master equation. In this paper, we show universal constraints on the relaxation times valid for any d-level GKLS master equations, which is a generalization of the well-known constraints for 2-level systems. Specifically, we show that any relaxation rate, the inverse-relaxation time, is not greater than half of the sum of all relaxation rates. Since the relaxation times are measurable in experiments, our constraints provide a direct experimental test for the validity of the GKLS master equations, and hence for the conditions of the complete positivity and Markovianity. </jats:p>

  18. Entropies in general probabilistic theories and their application to the Holevo bound Peer-reviewed

    Gen Kimura, Junji Ishiguro, Makoto Fukui

    Physical Review A　94　(4)　2016/10/17

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.94.042113 　

  19. Solution to the mean king's problem using quantum error-correcting codes Peer-reviewed

    Masakazu Yoshida, Gen Kimura, Takayuki Miyadera, Hideki Imai, Jun Cheng

    PHYSICAL REVIEW A　91　(5)　052326　2015/05

    DOI： 10.1103/PhysRevA.91.052326 　

    ISSN： 2469-9926

    eISSN： 2469-9934

  20. On affine maps on non-compact convex sets and some characterizations of finite-dimensional solid ellipsoids Peer-reviewed

    G. Kimura, K. Nuida

    Journal of Geometry and Physics　86　1-18　2014/12

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.geomphys.2014.06.004 　

  21. Determining eigenvalues of a density matrix with minimal information in a single experimental setting Peer-reviewed

    Tohru Tanaka, Yukihiro Ota, Mitsunori Kanazawa, Gen Kimura, Hiromichi Nakazato, Franco Nori

    Physical Review A　89　(1)　2014/01/21

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.89.012117 　

  22. Possibility of a minimal purity-measurement scheme critically depends on the parity of dimension of the quantum system Peer-reviewed

    T. Tanaka, G. Kimura, H. Nakazato

    Physical Review A　87　(1)　2013/01/03

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.87.012303 　

  23. On Physical Principles of Quantum Mechanics Invited Peer-reviewed

    Gen KIMURA

    Journal of the Japan Association for Philosophy of Science　40　(2)　79-84　2013

    Publisher: The Japan Association for Philosophy of Science

    DOI： 10.4288/kisoron.40.2_79 　

    ISSN： 0022-7668

    eISSN： 1884-1236

  24. Walter Lewin先生の公開授業 : ネット配信される大学の授業(<シリーズ>物理教育は今) Peer-reviewed

    峰 真如, 木村 元

    日本物理学会誌　68　(7)　483-484　2013

    DOI： 10.11316/butsuri.68.7_483 　

  25. Sufficient and Necessary Condition for Zero Quantum Entropy Rates under any Coupling to the Environment Peer-reviewed

    C{\'{e } }sar A. Rodr{\'{\i } }guez-Rosario, Gen Kimura, Hideki Imai, Al{\'{a } }n Aspuru-Guzik

    Physical Review Letters　106　(5)　2011/02/02

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physrevlett.106.050403 　

    ISSN： 0031-9007

    eISSN： 1079-7114

  26. On the general property of correlation Peer-reviewed

    Gen Kimura, Shuichi Tasaki

    97　(3)　421-428　2011

  27. Physical Equivalence of Pure States and Derivation of Qubit in General Probabilistic Theories

    Gen Kimura

    2010/12/24

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    In this paper, we investigate a characterization of Quantum Mechanics by two physical principles based on general probabilistic theories. We first give the operationally motivated definition of the physical equivalence of states and consider the principle of the physical equivalence of pure states, which turns out to be equivalent to the symmetric structure of the state space. We further consider another principle of the decomposability with distinguishable pure states. We give classification theorems of the state spaces for each principle, and derive the Bloch ball in 2 and 3 dimensional systems by these principles.

  28. Distinguishability measures and entropies for general probabilistic theories Peer-reviewed

    Gen Kimura, Koji Nuida, Hideki Imai

    Reports on Mathematical Physics　66　(2)　175-206　2010/10

    Publisher: Elsevier {BV}

    DOI： 10.1016/s0034-4877(10)00025-x 　

  29. Optimal observables for minimum-error state discrimination in general probabilistic theories Peer-reviewed

    Koji Nuida, Gen Kimura, Takayuki Miyadera

    Journal of Mathematical Physics　51　(9)　093505-093505　2010/09

    Publisher: {AIP} Publishing

    DOI： 10.1063/1.3479008 　

  30. Relation Between the Dynamics of the Reduced Purity and Correlations Peer-reviewed

    Gen Kimura, Hiromichi Ohno, Mil{\'{a } }n Mosonyi

    Open Systems & Information Dynamics　17　(03)　233-243　2010/09

    Publisher: World Scientific Pub Co Pte Lt

    DOI： 10.1142/s123016121000014x 　

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    <jats:p> General property of the relation between the dynamics of reduced purity and correlations in quantum mechanical systems is investigated. We show that a non-zero time-derivative of the reduced purity of a system implies the existence of non-zero correlations with its environment for any unbounded Hamiltonian with finite variance. This shows the impact of local dynamical information on the correlations, as well as the role of correlations in the mechanism of purity change. </jats:p>

  31. Optimal state discrimination in general probabilistic theories Peer-reviewed

    Gen Kimura, Takayuki Miyadera, Hideki Imai

    Physical Review A　79　(6)　2009/06/09

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.79.062306 　

  32. Quantum limits of measurements induced by multiplicative conservation laws: Extension of the Wigner-Araki-Yanase theorem Peer-reviewed

    Gen Kimura, Bernhard K. Meister, Masanao Ozawa

    Physical Review A　78　(3)　32106-32106　2008/09/08

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.78.032106 　

    ISSN： 1050-2947

  33. How to detect a possible correlation from the information of a subsystem in quantum-mechanical systems Peer-reviewed

    Gen Kimura, Hiromichi Ohno, Hiroyuki Hayashi

    Physical Review A　76　(4)　2007/10/22

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.76.042123 　

  34. Comments on “Best Conventional Solutions to the King’s Problem” International-journal Peer-reviewed

    Gen Kimura, Hajime Tanaka, Masanao Ozawa

    Zeitschrift für Naturforschung A　62　(3-4)　152-156　2007/04/01

    Publisher: Walter de Gruyter {GmbH}

    DOI： 10.1515/zna-2007-3-406 　

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    <jats:p>Conventional solutions of the (Mean) King’s problem without using entanglement have been investigated by P. K. Aravind, Z. Naturforsch. 58a, 682 (2003). We report that the upper bound for the success probability claimed is not valid in general but we give a condition for the claim to be justified.</jats:p>

  35. On the assumption of initial factorization in the master equation for weakly coupled systems II: Solvable models Peer-reviewed

    K. Yuasa, S. Tasaki, P. Facchi, G. Kimura, H. Nakazato, I. Ohba, S. Pascazio

    Annals of Physics　322　(3)　657-676　2007/03

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.aop.2006.06.003 　

  36. On the assumption of initial factorization in the master equation for weakly coupled systems I: General framework Peer-reviewed

    S. Tasaki, K. Yuasa, P. Facchi, G. Kimura, H. Nakazato, I. Ohba, S. Pascazio

    Annals of Physics　322　(3)　631-656　2007/03

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.aop.2006.06.004 　

  37. Solution to the mean king's problem with mutually unbiased bases for arbitrary levels International-journal Peer-reviewed

    Gen Kimura, Hajime Tanaka, Masanao Ozawa

    Physical Review A　73　(5)　050301(R)　2006/05/05

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevA.73.050301 　

    ISSN： 1050-2947

  38. Projection Operator Method for Open Quantum Systems Revisited(Fundamental Problems and Applications of Quantum Field Theory)

    Yuasa K., Tasaki S., Facchi P., Kimura G., Nakazato H., Ohba I., Pascazio S.

    Soryushiron Kenkyu Electronics　113　(1)　A15　2006

    Publisher: Soryushiron Kenkyu Editorial Office

    DOI： 10.24532/soken.113.1_A15 　

  39. The Bloch-Vector Space for N-Level Systems: the Spherical-Coordinate Point of View Peer-reviewed

    Gen Kimura, Andrzej Kossakowski

    Open Systems & Information Dynamics　12　(03)　207-229　2005/09

    Publisher: World Scientific Pub Co Pte Lt

    DOI： 10.1007/s11080-005-0919-y 　

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    <jats:p> Bloch-vector spaces for N-level systems are investigated from the spherical-coordinate point of view in order to understand their geometrical aspects. We present a characterization of the space by using the spectra of (orthogonal) generators of SU (N). As an application, we find a dual property of the space which provides an overall picture of the space. We also provide three classes of quantum-state representations based on actual measurements and discuss their state-spaces. </jats:p>

  40. A Note on Positive Maps and Classification of States Peer-reviewed

    Gen Kimura, Andrzej Kossakowski

    Open Systems &amp; Information Dynamics　12　(01)　1-11　2005/03

    Publisher: World Scientific Pub Co Pte Lt

    DOI： 10.1007/s11080-005-0482-6 　

    ISSN： 1230-1612

    eISSN： 1793-7191

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    The relation between positive maps on Mn and subsets of self-adjoint elements from Mn ⊗ Mn is investigated. It has been shown that there exists the isomorphism between the set of all positive normalized maps on Mn and the subset of separable states on Mn ⊗ Mn.

  41. A Class of Linear Positive Maps in Matrix Algebras II Peer-reviewed

    Gen Kimura, Andrzej Kossakowski

    Open Systems &amp; Information Dynamics　11　(04)　343-358　2004/12

    Publisher: World Scientific Pub Co Pte Lt

    DOI： 10.1007/s11080-004-6625-3 　

    ISSN： 1230-1612

    eISSN： 1793-7191

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    We provide a class of linear trace preserving positive maps on matrix algebras which is a generalization of that in [7]. A systematic construction by means of spectra of generators of SU (n) is discussed.

  42. The Bloch vector for N-level systems Peer-reviewed

    Gen Kimura

    Physics Letters A　314　(5-6)　339-349　2003/08

    Publisher: Elsevier {BV}

    DOI： 10.1016/s0375-9601(03)00941-1 　

  43. Kraus representation in the presence of initial correlations Peer-reviewed

    Hiroyuki Hayashi, Gen Kimura, Yukihiro Ota

    Physical Review A　67　(6)　2003/06/26

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.67.062109 　

  44. Restriction on relaxation times derived from the Lindblad-type master equations for two-level systems Peer-reviewed

    Gen Kimura

    Physical Review A　66　(6)　2002/12/31

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.66.062113 　

  45. Bifurcation phenomenon in spin relaxation (vol 89, art no 140403, 2002)

    G Kimura, K Yuasa, K Imafuku

    PHYSICAL REVIEW LETTERS　89　(16)　2002/10

    DOI： 10.1103/PhysRevLett.89.169906 　

    ISSN： 0031-9007

  46. Bifurcation Phenomenon in Spin Relaxation Peer-reviewed

    Gen Kimura, Kazuya Yuasa, Kentaro Imafuku

    Physical Review Letters　89　(14)　2002/09/16

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physrevlett.89.140403 　

  47. 2次元量子Markov過程と緩和定数(量子情報とその周辺分野の解析的研究)

    木村, 元, 湯浅, 一哉, 今福, 健太郎

    数理解析研究所講究録　1266　21-30　2002/05

    Publisher: 京都大学数理解析研究所

    ISSN： 1880-2818

  48. Master equation of the Lindblad form based on a microscopic Hamiltonian through stochastic limit approximation : For rapidly decaying systems (Analytical Study of Quantum Information and Related Fields)

    Yuasa, Kazuya, Kimura, Gen, Imafuku, Kentaro

    1266　133-141　2002/05

    Publisher:

    ISSN： 1880-2818

  49. 9. Rapidly decaying spin system based on the stochastic limit approach(The 9th Symposium on Non-Equilibrium Statisitical Physics)

    Kimura, G., Yuasa, K., Imafuku, K.

    77　(5)　937-940　2002/02/20

    Publisher:

    ISSN： 0525-2997

  50. Stochastic limit approximation for rapidly decaying systems Peer-reviewed

    Gen Kimura, Kazuya Yuasa, Kentaro Imafuku

    Physical Review A　63　(2)　2001/01/10

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physreva.63.022103 　

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Misc. 8

  1. ベルの不等式が問いかける 実在・局所性・自由意志, 語り：木村 元 聞き手：古田 彩

    木村 元

    日経サイエンス　2023/12

  2. （巻頭言）若き（？）物理学者の悩み

    木村 元

    数理科学　2023/05

  3. QBism:量子×ベイズ――量子情報時代の新解釈

    H. C, フォン・バイヤー, 木村 元, 松浦 俊輔

    2018/03

  4. 量子力学に現れる非局所性の意味

    木村 元

    数理科学　2014/12

  5. 情報から生まれる量子力学

    木村 元

    日経サイエンス　2013/07

  6. Mutually Unbiased Basisと有限幾何について

    吉田雅一, 木村元, 宮寺隆之, CHENG Jun

    情報理論とその応用シンポジウム予稿集(CD-ROM)　36th　2013

  7. 量子力学の原理を求めて

    木村元

    数理科学　2009/12

  8. 26pRF-2 『Quantum Limits of Measurements induced by Multiplicative Conservation Laws : An Extension of the WAY Theorem』

    Kimura G., Meister B.K., Ozawa M.

    Meeting Abstracts of the Physical Society of Japan　63　(0)　206-206　2008

    Publisher: The Physical Society of Japan

    DOI： 10.11316/jpsgaiyo.63.1.2.0_206_4 　

    ISSN： 1342-8349

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Books and Other Publications 6

  1. 量子情報科学入門 第2版

    石坂 智, 小川 朋宏, 河内 亮周, 木村 元, 林 正人

    共立出版　2024/06/05

    ISBN: 4320125797

  2. 量子の不可解な偶然 : 非局所性の本質と量子情報科学への応用

    Gisin, N. (Nicolas), 木村, 元 (量子力学), 筒井, 泉

    共立出版　2022/09

    ISBN: 9784320036222

  3. Introduction to quantum information science

    Masahito Hayashi, Satoshi Ishizaka, Akinori Kawachi, Gen Kimura, Tomohiro Ogawa

    Springer　2015

    ISBN: 9783662435014

  4. 量子情報科学入門

    石坂 智, 小川 朋宏, 河内 亮周, 木村 元, 林 正人

    共立出版　2012/06/08

    ISBN: 4320122992

  5. Decoherence suppression in quantum systems 2008

    中原, 幹夫, Rahimi, Robabeh, SaiToh, Akira

    World Scientific　2010

    ISBN: 9789814295833

  6. マーミン 量子コンピュータ科学の基礎

    N.D.マーミン著, 木村元訳

    丸善　2009/07

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Research Projects 3

  1. 量子論及び量子情報理論における普遍則

    木村 元

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 基盤研究(C)

    Institution: 芝浦工業大学

    2024/04 - 2029/03

  2. Information theory based on general probabilistic theories and its application to the foundation of quantum mechanics

    Kimura Gen

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Young Scientists (B)

    Institution: Shibaura Institute of Technology

    2017/04/01 - 2022/03/31

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    We investigated the foundations of quantum theory and quantum information theory mainly based on general probabilistic theories. We clarified the universal relationship between the geometrical structure of the state space and information storing, and provided an information-theoretic understanding of simple questions such as why only qubit systems have point symmetry (Bloch Ball). In addition, the principle of information symmetry was developed and various information quantities were characterized based on general probabilistic theories. We also discovered the universal law of relaxation times for completely positive dynamics and a new relaxed Bell's inequality by introducing a hiddeness which characterizes the extent how much we need a hidden variable. Quantum teleportation based on the vacuum entanglement was also studied where we have clarified the optimal procol with a given entanglement.

  3. On correlation in general probabilistic theories and its application to quantum information theory

    KIMURA Gen

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Young Scientists (B)

    2010/04/01 - 2014/03/31

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    We studied a foundation of quantum mechanics and quantum information theory using the general probabilistic theories, which is considered to provide the most general framework of operationally valid probability theories. One of the goal of this study is to derive quantum mechanics based on purely physical principles, with the help of the recent development of the quantum information science. In particular, we have derived qubit system with appropriate physical principles and found general properties of correlations applicable to unconditionally secure key distribution.