Algebraic rates of stability for front-type modulated waves in Ginzburg Landau equations

Abstract

We consider the stability of front-type modulated waves in the complex Ginzburg-Landau equation (CGL). The waves occur in the bistable regime (e.g. of the quintic CGL) and connect the zero state to a spatially homogenous state oscillating in time. For initial perturbations that decay at a certain algebraic rate, we prove convergence to the wave with asymptotic phase. The convergence holds in algebraically weighted Sobolev norms and with an algebraic rate in time, where the asymptotic phase is approached by one order less than the profile. On the technical side we use the theory of exponential trichotomies to separate the spatial modes into growing, weakly decaying, and strongly decaying ones. This allows us to derive resolvent and semigroup estimates in weighted Sobolev norms and to close the argument with a Gronwall lemma involving algebraic weights.