Antiphase synchronism in chaotic systems

We report our finding and analysis of a type of synchronism that occurs in chaotic systems with symmetry. Specifically, we find that the amplitudes of the dynamical variables of such a system can be synchronized with those of its replica, but that the variables can have different signs with respect to each other. This type of antiphase chaotic synchronism is observable in wide parameter regimes even for hyperchaotic systems. The mechanism of the synchronism suggests a systematic and a priori way to construct synchronizable chaotic systems. Application to nonlinear digital communication is pointed out.