In its simplest form, optomechanics amounts to two complementary coupling effects: mechanical motion changes the path followed by light, but light (through radiation pressure) can drive the mechanical resonator into motion as well. Optomechanics allows one to control resonator motion by laser cooling down to the quantum ground state, or to control light by using back-action in optical measurements and in quantum optics. Its main applications are optomechanical sensors to detect tiny mechanical motions and weak forces, cold damping and laser cooling, and quantum optics. The objectives of this chapter are to provide a brief account of the history of the field, together with its fundamentals. We will in particular review both classical and quantum aspects of optomechanics, together with its applications to high-sensitivity measurements and to control or cool mechanical resonators down to their ground state, with possible applications for tests of quantum theory or for quantum information.
Quantum ground state and single-phonon control of a mechanical resonator
