# Faculty

## Tooru Taniguchi

### Major research fields

Nonequilibrium statistical mechanics, Chaotic dynamics

Statistical mechanics is a physical theory to describe macroscopic phenomena based on the microscopic dynamics. It has been greatly successful in helping us to understand a wide variety of equilibrium states in macroscopic systems, but many physicists still try to extend it to describe non-equilibrium phenomena such as heat and particle flows, etc. My research interest is to develop such non-equilibrium statistical mechanics and thermodynamics from a microscopic point of view. To achieve this purpose I have worked on chaotic dynamics and complex systems. The chaos in dynamical systems is characterized by a rapid exponential divergence of a small initial error in time, so it causes unpredictability in deterministic dynamical systems. Such a dynamical property of chaotic systems, the so-called the dynamical instability, is expected to be a foundation of statistical mechanics. I am also interested in how statistical mechanical behaviors could appear in small systems. Differently from macroscopic systems in which fluctuations are suppressed by the law of large numbers, physical quantities in small systems fluctuate in time. The dynamical fluctuation can be described by stochastic dynamics with random variables. I have tried to describe and understand fluctuating phenomena in small and non-equilibrium systems by the stochastic approach. Another research subject, which I am interested in, is a theoretical description of mesoscopic phenomena on a scale of nanometers in which the quantum mechanical effects play an important role. A recent development in nanotechnology makes it possible to carry out experiments on various structural and dynamical properties of quantum systems. I have worked on transport properties and quantum interference effects in such mesoscopic systems.

### Major relevant publications

- "Escape Behavior of Quantum Two-Particle Systems with Coulomb Interactions", Tooru Taniguchi and Shin-ichi Sawada, Physical Review E 83, 026208 (2011).
- "Onsager-Machlup theory for nonequilibrium steady states and fluctuation theorems", Tooru Taniguchi and E. G. D. Cohen, Journal of Statistical Physics 126, 1 (2007).
- "Time-Oscillating Lyapunov Modes and the Momentum Autocorrelation Function", Tooru Taniguchi and Gary P. Morriss, Physical Review Letters 94, 154101 (2005).
- "Steady Shear Flow Thermodynamics Based on a Canonical Distribution Approach", Tooru Taniguchi and Gary P. Morriss, Physical Review E 70, 056124 (2004).
- "Friedel Phases and Phases of Transmission Amplitudes in Quantum Scattering Systems", Tooru Taniguchi and Markus Büttiker, Physical Review B 60, 13814 (1999).