Poincare recurrence and measure of hyperbolic and nonhyperbolic chaotic attractors

We study Poincare recurrence of chaotic attractors for regions of finite size. Contrary to the standard case, where the size of the recurrent regions tends to zero, the measure is not supported anymore solely by unstable periodic orbits inside it, but also by other special recurrent trajectories, located outside that region. The presence of the latter leads to a deviation of the distribution of the Poincare first return times from a Poissonian. Consequently, by taken into account the contribution of these recurrent trajectories, a corrected estimate of the measure can be provided. This has wide experimental implications, as in the laboratory all returns can exclusively be observed for regions of finite size only.