InaRIS Fellow (2026-2035)

Takahiro Sagawa

Graduate School of Engineering, The University of TokyoProfessor*Profile is at the time of the award.

2026InaRISScience & Engineering

Research topics
Nonlinear and nonequilibrium topology and its application to thermodynamics
Keyword
Summary
Nonlinearity and nonequilibrium play crucial roles in a wide range of systems, from biology to quantum physics. In this project, I investigate a topological perspective on such nonlinear and nonequilibrium systems and reveal the principles that govern stable behaviors robust against perturbation. Focusing on, e.g. classical stochastic processes and nonlinear oscillators, where topology has rarely been discussed so far, I aim to open a new frontier of topological physics. I will further apply these observations to thermodynamics to propose design principles for energy-efficient heat engines and information-processing devices.

Message from Fellow


Citation

Dr. Takahiro Sagawa formulated a theoretical framework integrating the concept of information into thermodynamics, effectively founding the field now known as “Information Thermodynamics." The relationship between information and energy has been a subject of debate since the “Maxwell’s Demon” paradox, followed by the thought experiments of Szilard, Bennett, and Landauer. However, Sagawa’s profound contribution lies in his ability to formalize these concepts into a quantitative and universal mathematical framework. As the field has matured through extensive theoretical and experimental developments, Sagawa has remained its consistent leader. Furthermore, he has achieved fundamental breakthroughs in thermodynamics resource theory based on quantum information, as well as the problem of thermalization in isolated quantum many-body systems. Through these achievements, he has pioneered the fusion of thermodynamics and quantum information.

Dr. Sagawa’s proposed research aims to further expand his scientific horizons by introducing topology as a new axis, alongside thermodynamics and quantum information. Since the discovery of the quantum Hall effect, research on the topological properties of physical phenomena has progressed significantly in quantum systems, particularly in the classification of symmetry-protected topological phases. Recently, this has extended to non-Hermitian systems, classical fluids, and active matter. Dr. Sagawa himself has proposed topological numbers for nonlinear systems, demonstrated the bulk-edge correspondence, and elucidated transitions to chaos. In this project, he intends to deepen and expand these results to construct a new theoretical system through integration with information thermodynamics.

Specifically, regarding the topology of non-equilibrium systems, he aims to achieve topological control over stochastic processes and quantum master equations describing interacting many-body systems. He identifies many-body information thermodynamics as a phenomenon deeply intertwined with this framework. By performing topological characterization of measurement and feedback in many-body systems, he seeks to identify unconventional contributions to entropy production. Furthermore, concerning the topology of nonlinear systems, he has set forth an ambitious plan for the “topological classification of nonlinear systems” by merging topology with dynamical systems. This endeavor holds the potential to create an entirely new field of mathematics.

Dr. Sagawa’s challenge is expected to weave together the concepts of thermodynamics, information, quantum mechanics, and topology on the horizon of non-equilibrium science to establish an unprecedented theoretical framework. His sincere dedication to breaking through the boundaries of existing academic disciplines and deriving new universal principles embodies the core philosophy of the InaRIS Fellowship, which encourages “grand questions that challenge scientific common sense” through long-term, ten-year support. The selection committee holds the highest expectations for the overwhelming development of his work.



Message from Fellow

I have pursued research mainly in nonequilibrium thermodynamics, thermodynamics of information, and quantum information theory. Yet, topology has long been a subject of deep interest to me since my undergraduate days, from both physical and mathematical perspectives. With this grant, I aim to substantially advance the study of topology in nonlinear and nonequilibrium systems and make topology one of the central topics of my research.

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