Single photons provide unique advantages that make this architecture ideally suited for quantum computation and quantum simulation. In particular the low-noise properties and the ease of manipulation at the individual particle level allow for the simulation of particular interesting questions in quantum chemistry, quantum biology and solid-state physics. Moreover, the advantage of the photons' mobility makes optical quantum systems unprecedented for quantum random walks and thus for mimicking quantum transport phenomena. Here we give an overview of the state-of-the-art technology for the photon generation using spontaneous parametric down-conversion and for the high-efficient detection using superconducting single-photon nanowire detectors. In addition we review some recent photonic quantum simulations and explain novel quantum computation architectures that exploit the superposition of the orders of quantum gates.