This project aims at the efficient realization of quantum interfaces for high-fidelity conversion and coherent manipulation of quantum states of phonons and of photons at vastly distinct wavelengths. We will consider different experimental platforms, e.g. photonic crystal cavities, nonlinear crystalline resonators, graphene-based nanoelectromechanical systems, and nanomembranes, with the aim of implementing interfaces that are able to interact simultaneously in a tunable way with optical and microwave fields. State transfer and controlled dynamics between radiation modes at completely different frequencies and between photons and phonons will be accomplished using diverse strategies, e.g. by tailoring the coupling of the interface with the fields, by exploiting electromagnetically-induced transparency, or the nonlinearities achievable in the strong coupling regime. The project results will enable new regimes for radio- and microwave electro-magnetic field detection, allowing quantum-limited amplification and readout of microwave and radio-frequency radiation. At the same time solid-state quantum devices which are now mainly manipulated by radiofrequencies and/or microwaves will become efficiently coupled to and controlled by optical fields.