Synchronization of spatio-temporal chaos as an absorbing phase transition: a study in 2+1 dimensions

The synchronization transition between two coupled replicas of spatio-temporal chaotic systems in 2+1 dimensions is studied as a phase transition into an absorbing state—the synchronized state. Confirming the scenario drawn in (1+1)-dimensional systems, the transition is found to belong to two different universality classes—multiplicative noise (MN) and directed percolation (DP)—depending on the linear or nonlinear character of damage spreading occurring in the coupled systems. By comparing a coupled map lattice with two different stochastic models, accurate numerical estimates for MN in 2+1 dimensions are obtained. Finally, aiming to pave the way for future experimental studies, slightly non-identical replicas have been considered. It is shown that the presence of small differences between the dynamics of the two replicas acts as an external field in the context of absorbing phase transitions and can be characterized in terms of a suitable critical exponent.