Spatial coherence and temporal chaos in macroscopic systems with asymmetrical couplings

Coupled map lattices with asymmetric short-range couplings are studied analytically and numerically. It is shown that with open boundary conditions these systems exhibit spatially uniform, but temporally chaotic states that are stable even in the thermodynamic limit. The stability of this state is associated with the appearance of a gap at zero wave number in the spectrum of the linear operator describing the fluctuations about the uniform state. The long-range order is unstable to noise. We calculate the finite coherence length of the chaotic state in the presence of weak noise.