NOISE ENHANCED STABILITY IN AN UNSTABLE SYSTEM

We experimentally detect noise enhanced stability in an unstable physi cal system. The average escape time from a metastable, periodically dr iven, system is measured in the stable and unstable regimes in a noisy environment. In the unstable regime, we measure that the average esca pe time has a maximum for a finite value of the noise intensity. The s caling properties of the average escape time and of the variance of es cape times are compared with the predictions obtained for a system in a marginal state.