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Center for Nonlinear Studies |
Fundamental microscopic laws such as Newtons laws and quantum mechanics are reversible; however, most microscopic systems give rise to irreversible behavior. The origin of irreversible behavior is therefore recognized as an important issue and persistent theme in physics. We study a system which undergoes transitions between reversible and irreversible behavior in order to better understand the onset of irreversibly and loss of predictability. When a magnetic field is applied to a type II superconductor it penetrates the material in the form of quantized magnetic flux lines called vortices. Using numerical simulations, we study vortices shaken by an ac drive in the presence of a random pinning substrate, made up of attractive parabolic wells. Even in the absence of thermal fluctuations, we observe both reversible and irreversible regimes of vortex motion. The irreversible behavior arises as a result of increasing interaction between the vortices. Intermittent transitions between the two regimes occur at a frequency which is determined by the vortex density as well as the amplitude and period of the driving force. By characterizing this system we show how irreversibility emerges statistically from a deterministic many-body dynamical system.
Host: Cynthia Reichhardt and Charles Reichhardt