Tanaka, Shu



Faculty of Science and Technology, Department of Applied Physics and Physico-Informatics (Yagami)


Associate Professor

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Career 【 Display / hide

  • 2008.04

    The University of Tokyo, Institute of Solid State Physics, Postdoctoral fellow

  • 2010.04

    Kindai University, Quantum Computing Center, 博士研究員

  • 2011.04

    The University of Tokyo, Department of Chemistry, Research Fellowship for Young Scientists, Japan Society for the Promotion of Science

  • 2014.04

    Kyoto University, Yukawa Institute for Theoretical Physics, Postdoctoral Fellow (Yukawa Fellow)

  • 2014.10

    Kyoto University, Faculty of Integrated Human Studies, Part-time Lecturer

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Academic Background 【 Display / hide

  • 1999.04

    Tokyo Institute of Technology, School of Science, Department of Physics

    Japan, University, Graduated

  • 2003.04

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

    Japan, Graduate School, Completed, Master's course

  • 2005.04

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

    Japan, Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide

  • Ph. D, The University of Tokyo, Coursework, 2008.03

    Slow Dynamics in Frustrated Magnetic Systems


Research Areas 【 Display / hide

  • Mathematical physics/Fundamental condensed matter physics

Research Keywords 【 Display / hide

  • 量子アニーリング

  • イジングマシン

  • 物性理論

  • 統計力学

  • 計算物理学


Books 【 Display / hide

Papers 【 Display / hide

  • Solving constrained slot placement problems using an ising machine and its evaluations

    Kanamaru S., Kawamura K., Tanaka S., Tomita Y., Togawa N.

    IEICE Transactions on Information and Systems (IEICE Transactions on Information and Systems)  E104D ( 2 ) 226 - 236 2021.02

    ISSN  09168532

     View Summary

    Ising machines have attracted attention, which is expected to obtain better solutions of various combinatorial optimization problems at high speed by mapping the problems to natural phenomena. A slot-placement problem is one of the combinatorial optimization problems, regarded as a quadratic assignment problem, which relates to the optimal logic-block placement in a digital circuit as well as optimal delivery planning. Here, we propose a mapping to the Ising model for solving a slot-placement problem with additional constraints, called a constrained slot-placement problem, where several item pairs must be placed within a given distance. Since the behavior of Ising machines is stochastic and we map the problem to the Ising model which uses the penalty method, the obtained solution does not always satisfy the slot-placement constraint, which is different from the conventional methods such as the conventional simulated annealing. To resolve the problem, we propose an interpretation method in which a feasible solution is generated by post-processing procedures. We measured the execution time of an Ising machine and compared the execution time of the simulated annealing in which solutions with almost the same accuracy are obtained. As a result, we found that the Ising machine is faster than the simulated annealing that we implemented.

  • Designing Metamaterials with Quantum Annealing and Factorization Machines

    Koki Kitai, Jiang Guo, Shenghong Ju, Shu Tanaka, Koji Tsuda, Junichiro Shiomi, and Ryo Tamura

    Physical Review Research 2   013319-1 - 013319-10 2020.03

    Research paper (scientific journal), Joint Work, Accepted

  • A new LDPC code decoding method: Expanding the scope of ising machines

    Tawada M., Tanaka S., Togawa N.

    Digest of Technical Papers - IEEE International Conference on Consumer Electronics (Digest of Technical Papers - IEEE International Conference on Consumer Electronics)  2020-January 2020.01

    ISSN  9781728151861

     View Summary

    Low-density parity-check (LDPC) codes have previously been considered as combinatorial optimization problems (COPs) in respect to its decoding. However, after defining it as such, none have gone so far as to convert the LDPC code into a quadratic unconstrained binary optimization (QUBO) problem. Thus, a new method is created: one that converts the LDPC code to a QUBO problem, inputs the QUBO problem into Ising machines (computers based on the Ising model that are designed to solve the QUBO problem), obtains the QUBO solution and converts it to a LDPC solution. By utilizing an actual Ising machine, LDPC solutions with code length of 256-bits have been obtained with an accuracy of 93.9% by average annealing time 214.0ms. The benefit of this newfound methodology goes beyond its theoretical imprint of obtaining LDPC solutions more accurately. It has only been a few years since the Ising machine has been developed. Therefore, in formulating this method, one expands the currently scope of studies involving Ising machines, helping current and future researchers unlock its full range of capabilities and possibilities.

  • Theory of Ising Machines and a Common Software Platform for Ising Machines

    Shu Tanaka, Yoshiki Matsuda, and Nozomu Togawa

    Proceedings of 25th Asia and South Pacific Design Automation Conference (ASP-DAC 2020) 9C-1 (Proceedings of the Asia and South Pacific Design Automation Conference, ASP-DAC)  2020-January   659 - 666 2020

    Research paper (international conference proceedings), Joint Work, Accepted,  ISSN  9781728141237

     View Summary

    Ising machines are a new type of non-Neumann computer that specializes in solving combinatorial optimization problems efficiently. The input form of Ising machines is the energy function of the Ising model or quadratic unconstrained binary optimization form, and Ising machines operate to search for a condition to minimize the energy function. We describe the theory of Ising machines and the present status of the Ising machines, software for Ising machines, and applications using Ising machines.

  • How to Reduce the Bit-width of an Ising Model by Adding Auxiliary Spins

    Oku D., Tawada M., Tanaka S., Togawa N.

    IEEE Transactions on Computers (IEEE Transactions on Computers)   2020

    ISSN  00189340

     View Summary

    Annealing machines have been developed as non-von Neumann computers aimed at solving combinatorial optimization problems efficiently. To use annealing machines for solving combinatorial optimization problems, we have to represent the objective function and constraints by an Ising model, which is a theoretical model in statistical physics. Further, it is necessary to transform the Ising model according to the hardware limitations. In the transformation, the process of effectively reducing the bit-widths of coefficients in the Ising model has hardly been studied so far. Thus, when we consider the Ising model with a large bit-width, a naive method, which means right bit-shift, has to be applied. Since it is expected that obtaining highly accurate solutions is difficult by the naive method, it is necessary to construct a method for efficiently reducing the bit-width. This paper proposes methods for reducing the bit-widths of interaction and external magnetic field coefficients in the Ising model and proves that the reduction gives theoretically the same ground state of the original Ising model. The experimental evaluations also demonstrate the effectiveness of our proposed methods.

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Reviews, Commentaries, etc. 【 Display / hide

  • イジングマシン技術の研究開発動向

    田中 宗

    技術解説書「拡大する量子コンピューティング その社会実装ポテンシャル」 (モバイルコンピューティング推進コンソーシアム(MCPC))   2020.03

    Introduction and explanation (others), Single Work

  • イジングマシンの動作原理と応用探索の最新動向

    田中 宗,松田 佳希

    表面と真空 63   96 - 103 2020

    Introduction and explanation (scientific journal), Joint Work

  • 量子アニーリングや関連技術のいまと未来:AQC2019 参加報告

    田中 宗,白井 達彦,藤井 啓祐

    日本物理学会誌 75 ( 5 ) 299 - 302 2020

    Introduction and explanation (scientific journal), Joint Work

  • 量子アニーリングの応用探索

    田中 宗,西村 直樹,棚橋 耕太郎

    数理科学 2019年7月号 673   47 - 53 2019.07

    Introduction and explanation (scientific journal), Joint Work

  • イジングマシンに関係するソフトウェア開発およびアプリケーション探索動向

    田中 宗

    量子コンピュータ/イジング型コンピュータ研究開発最前線 〜基礎原理・最新技術動向・実用化に向けた企業の取り組み〜 (情報機構)   2019.02

    Introduction and explanation (commerce magazine), Single Work

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Presentations 【 Display / hide

  • イジングマシンを用いたアミューズメントパークの経路最適化手法

    武笠 陽介、若泉 朋弥、田中 宗、戸川 望

    VLSI設計技術研究会, 2020.03, Oral Presentation(general)

  • イジング計算機による3次元直方体パッキング問題の解法

    金丸 翔、寺田 晃太朗、川村 一志、田中 宗、富田 憲範、戸川 望

    VLSI設計技術研究会, 2020.03, Oral Presentation(general)

  • 3 次元直方体パッキング問題のQUBOモデルマッピング

    金丸 翔、寺田 晃太朗、川村 一志、田中 宗、富田 憲範、戸川 望

    2020年電子情報通信学会総合大会, 2020.03, Oral Presentation(general)

  • イジングマシンにおける整数バイナリ変換の性能比較

    田村 健祐、白井 達彦、桂 法称、田中 宗、戸川 望

    日本物理学会第75回年次大会, 2020.03, Oral Presentation(general)

  • 温度効果を用いたイジングマシンにおける埋込アルゴリズムの理論

    白井 達彦、田中 宗、戸川 望

    2020年電子情報通信学会総合大会 依頼シンポジウムセッション「組合せ最適化専用イジングマシン周辺技術の現状と展望」, 2020.03, Oral Presentation(guest/special)

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Awards 【 Display / hide

  • 第9回日本物理学会若手奨励賞(領域11)

    田中 宗, 2015.03, 日本物理学会, 二次元量子多体系におけるエンタングルメントの研究

    Type of Award: Awards of National Conference, Council and Symposium.  Country: 日本

  • 東京大学大学院理学系研究科研究奨励賞(博士)

    田中 宗, 2008.03, 東京大学大学院理学系研究科

    Type of Award: Other Awards.  Country: 日本


Courses Taught 【 Display / hide











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Courses Previously Taught 【 Display / hide

  • ディジタルシステム設計

    早稲田大学基幹理工学部, 2019, Autumn Semester, Major subject, Lecture, Lecturer outside of Keio

  • オムニバス講義

    お茶の水女子大学, 2019, Autumn Semester, Major subject, Lecture, Lecturer outside of Keio

  • ディジタルシステム設計

    早稲田大学基幹理工学部, 2018, Autumn Semester, Major subject, Lecture, Lecturer outside of Keio

  • 物理学実験

    芝浦工業大学通信工学科, 2017, Laboratory work/practical work/exercise, Lecturer outside of Keio

  • Exercises for Fundamental Physics B IPSE Course

    早稲田大学先進理工学部, 2017, Autumn Semester, Major subject, Seminar

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