Stable resonances and signal propagation in a chaotic network of coupled units.

We apply the linear response theory developed by Ruelle [J. Stat. Phys. 95, 393 (1999)] to analyze how a periodic signal of weak amplitude, superimposed upon a chaotic background, is transmitted in a network of nonlinearly interacting units. We numerically compute the complex susceptibility and show the existence of specific poles (stable resonances) corresponding to the response to perturbations transverse to the attractor. Contrary to the poles of correlation functions they depend on the pair emitting-receiving units. This dynamic differentiation, induced by nonlinearities, exhibits the different ability that units have to transmit a signal in this network.