FLUCTUATIONS OF A STATIONARY NONEQUILIBRIUM INTERFACE

We study properties of interfaces between stationary phases of the two-dimensional discrete-time Toom model (north-east-center majority vote with small noise): phases not described by equilibrium Gibbs ensembles. Fluctuations in the interface maintained by mixed boundary conditions grow with distance much slower than in equilibrium systems; they have exponents close to 1/4 or 1/3, depending on symmetry, rather than 1/2, and have long-range correlations reminiscent of self-organized critical behavior. Approximate theories reproduce this behavior qualitatively and lead to novel nonlinear partial differential equations for the asymptotic profile.