Probing the Strong Boundary Shape Dependence of the Casimir Force

We study the geometry dependence of the Casimir energy for deformed metal plates by a path integral quantization of the electromagnetic field. For the first time, we give a complete analytical result for the deformation induced change in Casimir energy δE in an experimentally testable, nontrivial geometry, consisting of a flat and a corrugated plate. Our results show an interesting crossover for δE as a function of the ratio of the mean plate distance H, to the corrugation length λ: For λ≪H we find a slower decay ∼H^-4, compared to the H^-5 behavior predicted by the commonly used pairwise summation of van der Waals forces, which is valid only for λ≫H.