Thermally Driven Escape with Fluctuating Potentials: A New Type of Resonant Activation

The mean escape time $\overline{T}$ for thermal diffusion in a fluctuating metastable potential is investigated. A new type of “resonant activation” (minimum of $\overline{T}$ as a function of the correlation time $\tau$ of the potential fluctuations) is predicted analytically, explained in simple terms, and confirmed numerically. In its pure form it generically occurs for potentials without fluctuations near the barrier and the well. The effect is dominated by a minimum in the exponentially leading Arrhenius factor at a correlation time $\tau$ that stays finite for asymptotically small thermal and potential fluctuations.