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Sato Ryosuke

Faculty of Science Mathematics MathematicsAssistant Professor

Researcher basic information

■ Degree
  • Ph.D. in Mathematical Science, Nagoya University, Mar. 2022
■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Educational Organization

Career

■ Career
Career
  • Apr. 2025 - Present
    Hokkaido University, Faculty of Science Department of Mathematics, Assistant Professor, Japan

Research activity information

■ Papers
  • Variations on quantum de Finetti theorems and operator valued Martin boundaries: A Choquet–Deny approach
    Benoît Collins; Thierry Giordano; Ryosuke Sato
    Proceedings of the American Mathematical Society, 154, 3, 1233, 1249, American Mathematical Society (AMS), 15 Jan. 2026, [Peer-reviewed]
    Scientific journal,

    We revisit the quantum de Finetti theorem. We state and prove a couple of variants thereof. In parallel, we introduce an operator version of the Martin boundary on quantum groups and prove generalizations of Biane’s theorem. Our proof of the de Finetti theorem is new in the sense that it is based on an analogy with the theory of operator-valued Martin boundary that we introduce.

  • GICAR Algebras and Dynamics on Determinantal Point Processes: Discrete Orthogonal Polynomial Ensemble Case
    Ryosuke Sato
    Communications in Mathematical Physics, 405, 5, Springer Science and Business Media LLC, 25 Apr. 2024, [Peer-reviewed]
    Scientific journal
  • Multiplicative Characters and Gaussian Fluctuation Limits
    Ryosuke Sato
    Symmetry, Integrability and Geometry: Methods and Applications, SIGMA (Symmetry, Integrability and Geometry: Methods and Application), 03 Oct. 2023, [Peer-reviewed]
    Scientific journal, It is known that extreme characters of several inductive limits of compact groups exhibit multiplicativity in a certain sense. In the paper, we formulate such multiplicativity for inductive limit quantum groups and provide explicit examples of multiplicative characters in the case of quantum unitary groups. Furthermore, we show a Gaussian fluctuation limit theorem using this concept of multiplicativity.
  • Characters of infinite-dimensional quantum classical groups: BCD cases
    Ryosuke Sato
    Infinite Dimensional Analysis, Quantum Probability and Related Topics, 24, 04, World Scientific Pub Co Pte Ltd, 30 Dec. 2021, [Peer-reviewed]
    Scientific journal, We study the character theory of inductive limits of [Formula: see text]-deformed classical compact groups. In particular, we clarify the relationship between the representation theory of Drinfeld–Jimbo quantized universal enveloping algebras and our previous work on the quantized characters. We also apply the character theory to construct Markov semigroups on unitary duals of [Formula: see text], [Formula: see text], and their inductive limits.
  • Inductive limits of compact quantum groups and their unitary representations
    Ryosuke Sato
    Letters in Mathematical Physics, 111, 5, Springer Science and Business Media LLC, 24 Sep. 2021, [Peer-reviewed]
    Scientific journal
  • Quantized Vershik–Kerov theory and quantized central measures on branching graphs
    Ryosuke Sato
    Journal of Functional Analysis, 277, 8, 2522, 2557, Elsevier BV, Oct. 2019, [Peer-reviewed]
    Scientific journal
  • Type classification of extreme quantized characters
    RYOSUKE SATO
    Ergodic Theory and Dynamical Systems, 41, 2, 593, 605, Cambridge University Press (CUP), 06 Sep. 2019, [Peer-reviewed]
    Scientific journal, The notion of quantized characters was introduced in our previous paper as a natural quantization of characters in the context of asymptotic representation theory forquantum groups. As in the case of ordinary groups, the representation associated with any extreme quantized character generates a von Neumann factor. From the viewpoint of operator algebras (and measurable dynamical systems), it is natural to ask what is the Murray–von Neumann–Connes type of the resulting factor. In this paper, we give a complete solution to this question when the inductive system is of quantum unitary groups $U_{q}(N)$.
■ Lectures, oral presentations, etc.
  • Conservation operator processes and their CLT from asymptotic representation theory
    Rigorous Statistical Mechanics and Related Topics 2025, Nov. 2025
  • Conservation operator processes from asymptotic representation theory and their CLT
    Ryosuke Sato
    NCTS-AS Workshop on Free Probability Theory and Random Matrix Theory, Oct. 2025
  • Conservation operator processes from asymptotic representation theory and their CLT
    Ryosuke Sato
    Non-commutative Probability and Related Topics 2025, Oct. 2025
  • CAR algebras and stochastic dynamics on point processes
    Ryosuke Sato
    Mathematical aspects if quantum fields and related topics, May 2025
  • Operator-algebraic approach to stochastic processes on determinantal point processes
    Ryosuke Sato
    Non-commutative probability, random matrices and Lévy processes, Mar. 2025
  • The quantum de Finetti theorem and operator-valued Martin boundaries
    Ryosuke Sato
    作用素論・作用素環論研究集会, Nov. 2024
  • Dynamical relation between determinantal point processes and operator algebras
    Ryosuke Sato
    Rigorous Statistical Mechanics and Related Topics, Nov. 2024
  • Non-commutative random walks and the quantum de Finetti theorem
    Ryosuke Sato
    Non-commutative Probability and Related Topics 2024, Oct. 2024
  • CAR algebras and stochastic dynamics on random point processes
    Ryosuke Sato
    日本数学会2024年度秋季総合分科会, Sep. 2024
  • Stochastic dynamics on DPPs: From the viewpoint of operator algebras
    Ryosuke Sato
    無限粒子系、確率場の諸問題XVIII, Jan. 2024
  • Stochastic dynamics on DPPs and GICAR algebras
    Ryosuke Sato
    Random Interacting Systems, Scaling Limits, and Universality, Dec. 2023
  • On the interaction between determinantal point processes and operator algebras
    Ryosuke Sato
    Non-commutative Probability Theory, Random Matrix Theory and their Applications, Nov. 2023
  • Dynamics on DPPs and GICAR algebras
    Ryosuke Sato
    Non-Commutative Probability and Related Topics 2023, Oct. 2023
  • Stochastic dynamics on DPPs and GICAR algebras
    Ryosuke Sato
    The 21st Symposium Stochastic Analysis on Large Scale Interacting Systems, Oct. 2023
  • GICAR algebras and dynamics on determinantal point processes: orthogonal polynomial ensemble case
    Ryosuke Sato
    Recent Developments in Operator Algebras, Sep. 2023
  • Determinantal point processes and gauge-invariant CAR algebras
    Ryosuke Sato
    Random Matrices and Applications, Jun. 2023
  • Multiplicative characters and Gaussian fluctuation limits
    Ryosuke Sato
    Non-commutative Probability and Related Topics 2022, Nov. 2022
  • Markov processes on duals of quantum groups
    Ryosuke Sato
    Operator Algebras and Quantum Dynamical Systems, Feb. 2021
  • q-Schur generating functions and tensor porduct representations
    Ryosuke Sato
    作用素環の分類理論における新展開, Jan. 2020
  • Ergodic theoretical aspects of asymptotic representation theory
    Ryosuke Sato
    Nomcommutative probability and related fields, Nov. 2019
  • q-Schur generating functions and tensor product representations
    Ryosuke Sato
    Interactions between commutative and non-commutative probability, Aug. 2019
  • Asymptotic representation theory for quantum groups
    Ryosuke Sato
    Virginia Integrable Probability Summer School, Jun. 2019
  • Extremal quantized characters and biorthogonal ensembles
    Ryosuke Sato
    New Developments in Free Probability and Applications (Workshop2 : the applied perspective), Mar. 2019
  • Quantum group analogue of the Vershik-Kerov theory and the probability theory of the Gelfand-Tsetlin graph
    Ryosuke Sato
    Recent Developments in Operator Algebras, Sep. 2018
  • Quantized Vershik-Kerov theory and q-deformed Gelfand-Tsetlin graph
    Ryosuke Sato
    Random Matrices and their applications, May 2018
■ Affiliated academic society
  • Jun. 2024 - Present
    The Mathematical Society of Japan
■ Research Themes
  • Algebraic integrable probability theory
    Grants-in-Aid for Scientific Research
    Apr. 2022 - Mar. 2025
    佐藤 僚亮
    ランダム点過程を作用素環論の観点から研究した.特にランダム点過程のうち,その点同士の相関が行列式の形で表されるものを行列式点過程と呼び,ランダム行列理論や組合せ論,統計力学,表現論に関連する確率論などで研究されている.一方の作用素環論では,正準反交換関係を満たす生成元を持つCAR代数が様々な研究で重要な役割を果たしてきた.特に適当な設定の下で,CAR代数の状態は離散空間上のランダム点過程を与える.さらに状態がゲージ不変・準自由という性質を満たすとき,対応するランダム点過程は行列式点過程であることが,これまでの研究で知られていた.本研究では,この状態とランダム点過程との関係の発展を目指している.具体的には,作用素環論の立場から,ランダム点過程を不変測度とする確率過程を構成し,解析する理論を目指している.ここまでの業績として,ランダム点過程が直交多項式と関連する行列式点過程である場合,それを不変とするMarkov過程をCAR代数上の量子Markov半群から構成した.さらに構成したMarkov過程の推移確率と生成作用素の具体的な表示を与えた.この結果は論文にまとめ,Communication in Mathematical Physicsより出版された.またこの結果について研究会や研究セミナーなどで発表した.
    別の話題の研究として,コンパクト群の双対空間上の量子Markov半群と量子情報理論との関係に関する共同研究も行なった.特に量子情報理論における基本的な定理である量子de Finetti定理について新たな観点と新しい証明を与えた.
    Japan Society for the Promotion of Science, Grant-in-Aid for JSPS Fellows, Chuo University, 22KJ2770
  • 巨大な量子群上の調和解析と分岐グラフ上の確率論の融合的研究
    科学研究費助成事業
    Apr. 2019 - Mar. 2022
    佐藤 僚亮
    これまでA型コンパクト量子群の場合に続き,BCD型コンパクト量子群の帰納極限の漸近表現論を研究した.これに伴い量子普遍包絡環と量子群の漸近的表現論との関係も明確になるようにした.本研究の目的はコンパクト(量子)群の帰納極限の指標理論と帰納系が与える分岐グラフ上の確率論を研究することであった.A型コンパクト量子群の帰納系が与える分岐グラフの上の確率論と指標理論との関係は以前の研究で明らかになっていた.B型とC型のコンパクト量子群の帰納系が与える分岐グラフはBC型q-Gelfand-Tsetlinグラフと呼ばれ,その中心的確率測度やコヒーレント系といった概念が2018年に研究された.今回,これらがB型とC型のコンパクト量子群の帰納極限の指標と対応することを示した.これと以前の研究から直ちに,BC型q-Gelfand-Tsetlinグラフの中心的確率測度がその凸集合の中で端点であることエルゴード性を持つことが同値であることなどが示せる.またD型のコンパクト量子群の帰納極限の指標の一部はBC型q-Gelfand-Tsetlinグラフの中心的確率測度やコヒーレント系と対応することも示した.
    コンパクト(量子)群の帰納極限の指標は,さらに分岐グラフのパス空間上の確率過程とも関係する.特にABC型の普通のコンパクト群の場合,それらの帰納極限の端点指標はある種の乗法性をもち,この性質が分岐グラフのパス空間上の確率過程を研究するときに重要である.これと同様の性質を持つ量子群の指標をA型の場合は昨年度,B型とC型の場合は今年度構成した.これらの指標が与えるマルコフ過程の生成作用素や推移確率の明示式も与えた.こうした研究は可積分確率論と呼ばれる確率論や可積分系,統計力学の研究と表現論との関係を理解するのに役立つと期待される.
    日本学術振興会, 特別研究員奨励費, 名古屋大学, 19J21098