Nonlinear Dynamics group

  • Shin-ichi Sasa (
  • Andreas Dechant (

We aim to build a new theoretical framework while exploring qualitatively new phenomena in emergent behaviors in non-equilibrium systems and biological functions by materials. Each research topic is considered independently by the members. As a reference, in 2020, papers on the following subjects are published. A new theory on the two-dimensional phase order under shear flow, a theory of turbulence near a gas-liquid critical point, a theory on new inequalities of fluctuations, and a proposal of game-theoretical thermodynamics.
(group website)

Fluid Physics group

  • Toh Sadayoshi (
  • Takeshi Matsumoto (

Our goal is to uncover theoretically fundamental laws of fluid phenomena ranging from human scale up to cosmic scale. Essential aspects of those phenomena lie in nonlinearity, nonequilibrium, and infinite degrees of freedom. To tackle them, what is needed is to develop novel views and theoretical methods by using numerical simulations and recent mathematical results. Our current research topics include dynamical-systems approach to turbulence (invariant solutions, subcritical transitions etc.), turbulent transport (mixing and diffusion), nonlinear waves as elementary processes, and collective motions of self-propelled agents such as birds.
(group website)

Phase Transition Dynamics group

  • Takeaki Araki (
  • Hikaru Kitamura (

Our central subject is the dynamics of phase transitions, phase separations, and pattern formations by theoretical analyses and numerical simulations. As a target of nonequilibrium and nonlinear physics, we study soft matter such as polymers, liquid crystals, and colloids, including disordered electron systems in fluid metals. We put an emphasis on interdisciplinary and unexplored subjects, making intensive collaborations with experimental groups.
(group website)

Nonequilibrium Dynamics group

  • Shinji Takesue (

Our goal is to clarify the origin of irreversibility and the appearance of diffusive motion from deterministic dynamics. For that purpose, we study the possible connection between the phase-space structure and macroscopic behavior using lattice dynamical models such as cellular automata.
(group website)