We study theoretically and numerically the steady state diffusion controlled reaction A + B → Ø, where currents J of A and B particles are applied at opposite boundaries. For a reaction rate λ, and equal diffusion constants D, we find that when λJ-1/2D-1/2≪1 the reaction front is well described by mean-field theory. However, for λJ-1/2D-1/2≫1, the front acquires a Gaussian profile - a result of noise induced wandering of the reaction front center. We make a theoretical prediction for this profile which is in good agreement with simulation. Finally, we investigate the intrinsic (nonwandering) front width and find results consistent with scaling and field theoretic predictions.
