Experiments on large fluctuations

Noise-induced fluctuations in non-linear systems are studied theoretically and experimentally for finite noise intensity. After reviewing briefly the basis of the Hamiltonian theory of fluctuations, the non-equilibrium distribution is calculated for the whole phase space, and determined numerically for different values of noise intensity. It is found that there are singularities which are shifted with respect to those seen in the zero-noise limit. A corresponding shift in the optimal escape path is observed and discussed. A new technique facilitating ultra-fast Monte Carlo simulation at extremely weak noise intensity is introduced and demonstrated