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Comprehensive List of Researchers "Information Knowledge"

Department of Complex Systems Science

Many-body Systems Science Group
Assistant Professor
Dr. of Philosophy
Research Field
Non-equilibrium Statistical Mechanics / Foundation of Thermodynamics / Nonlinear Dynamics

Current Research

Study on Universal Energy-Conversion Law in Non-Equilibrium/Nonlinear Dynamical Systems

I’m studying non-equilibrium thermodynamics/statistical mechanics, foundation of thermodynamics, and nonlinear dynamics. I’m especially interested in an interdisciplinary field where engineering ideas and fundamental physics ideas are intertwined. I have mainly been focusing on a basic question such as “What is a fundamental limitation when heat engines convert heat flux into power?” As is well known, the invention of steam engines in the era of the Industrial Revolution led to the discovery of the upper bound of the efficiency of heat engines by Carnot, and this is almost the origin of thermodynamics itself. However, this upper bound can be reached by an ideal Carnot cycle defined at zero power output (quasi-static limit). Actual power plants and heat devices operating in non-equilibrium states should output a finite power for a practical purpose, and understanding of universal law governing such non-equilibrium heat engines is of great importance from a practical as well as the fundamental physics point of view. In our previous works, we have for the first time confirmed the validity of theoretically-predicted universal upper bound of efficiency at maximum power of heat engines by using a finite-time Carnot cycle model, and elucidated its physical mechanism based on non-equilibrium thermodynamics. I believe that these results and ideas would have an impact not only on improving actual heat engines and heat devices but also on related fields such as biological physics, engineering, and nanotechnology.

More recently, I’m also working on theoretical studies on nonlinear dynamical systems (coupled oscillator systems) aiming for an application to complicated biological systems in my mind. We especially proposed a novel coarse-graining method that extracts essence of dynamical behaviors by reducing number of degrees of freedom in high-dimensional dynamical equations. We have also been developing “energetic of synchronization” by unifying concepts in non-equilibrium thermodynamics and nonlinear dynamics.


  • 03/2011: Department of Quantum and Condensed-Matter Physics, Graduate School of Science, Hokkaido University (Ph.D. in Physics)
  • 04/2010: JSPS Research Fellow (DC2) (Hokkaido University)
  • 04/2011: JSPS Research Fellow (PD) (The University of Tokyo)
  • 05/2012: Project Research Fellow at Department of Physics, Graduate School of Science, The University of Tokyo
  • 07/2012: Project Research Fellow at Center for Simulation Sciences, Ochanomizu University
  • 04/2013: JSPS Research Fellow (PD) (Ochanomizu University)
  • 04/2015: Assistant Professor, Graduate School of Information Science, Nagoya University

Academic Societies

  • The Physical Society of Japan


  1. Y. Izumida and K. Okuda, “Molecular kinetic analysis of a finite-time Carnot cycle”, EPL 83, 60003 (2008)
  2. Y. Izumida and K. Okuda, “Onsager coefficients of a finite-time Carnot cycle”, Phys. Rev. E 80, 021121 (2009)
  3. Y. Izumida and K. Okuda, “Work Output and Efficiency at Maximum Power of Linear Irreversible Heat Engines Operating with a Finite-Sized Heat Source”, Phys. Rev. Lett. 112, 180603 (2014)