  We describe how strong resonant interactions in multimode optomechanical
systems can be used to induce controlled nonlinear couplings between single
photons and phonons. Combined with linear mapping schemes between photons and
phonons, these techniques provide a universal building block for various
classical and quantum information processing applications. Our approach is
especially suited for nano-optomechanical devices, where strong optomechanical
interactions on a single photon level are within experimental reach.
