Fluctuational Dynamics of Extended Systems: Activation-Tunnel Frontier

The dynamics of systems in barrier structures is determined by the rate of the fluctuational decay of metastable states in a potential relief. The nature of the decay undergoes a qualitative change with a variation of the temperature. As the temperature decreases, thermal fluctuations freeze out and are replaced by quantum ones, which leads to a kind of phase transition in the dynamics. The transition temperature depends on the degree of metastability and can be controlled by an external load. This dependence is calculated for an extended nanosystem in an inclined periodic relief of the "washboard" type in a wide range of load changes. The obtained dependence generalizes the previously known results and can serve as the phase diagram of various dynamics mechanisms.