Different is more

We will show that diversity, in the form of quenched noise, can have a constructive effect in the dynamics of extended systems. We first consider a bistable phi-4 model composed by many coupled units and show that the global response to an external periodic forcing is enhanced under the presence of the right amount of diversity (measured as the dispersion in one of the parameters defining the model). As a second
example, we consider a system of active-rotators and show that while
they are at rest in the homogeneous case, the disorder introduced by the diversity suffices to trigger the appearance of common firings or pulses. Both effects require very simple ingredients and we expect the results presented here to be of interest in similar models of interest in the biological and social sciences. This is, hence, a simple modelization of the well known principle that "one should not put all the eggs in the same basket".