Optical quantum circuit combining tailored optical nonlinearities

We report our recent experimental demonstration of a KLM CNOT gate, a photonic quantum circuit to combine two efficient `artificial´ nonlinear elements. This experimental demonstration confirms the first step in the KLM `recipe´ for all-optical quantum computation, and should be useful for on-demand entanglement generation and purification. We will also report our activities toward the realization of nonlinear sign shift gate using diamond nano-crystals coupled to a microsphere cavity.