Light exerts mechanical action on matter through various mechanisms, the most famous being radiation pressure, with the associated picture of a photon bouncing on a perfectly reflective movable mirror and transferring twice its momentum. But still today, unambiguously observing the effects of radiation pressure remains a challenge. In the quantum domain, the radiation pressure interaction between a moving mirror and light stored in a cavity accepts a simple Hamiltonian formulation. But this Hamiltonian description is sometimes oversimplified and underestimates or misses other mechanical effects of light accompanying radiation pressure in experiments. In this chapter, we will not only address radiation pressure but also other relevant optical forces such as the optical gradient force, electrostriction, or the photothermal and optoelectronic forces, which are key in micro- and nanoscale devices and must all be controlled on an equal footing to fully harness the technological and scientific potential of miniature optomechanical systems.
Observability of radiation-pressure shot noise in optomechanical systems