Cavity opto-mechanics

Cavity optomechanics is a branch of physics which focuses on the interaction between light and mechanical objects on low-energy scales. It is a cross field of optics, quantum optics, solid-state physics and materials science. The motivation for research on cavity optomechanics comes from fundamental effects of quantum theory and gravity, as well as technological applications.

The name of the field relates to the main effect of interest, which is the enhancement of radiation pressure interaction between light (photons) and matter using optical resonators (cavities). It first became relevant in the context of gravitational wave detection, since optomechanical effects have to be taken into account in interferometric gravitational wave detectors. Furthermore, one may envision optomechanical structures to allow the realization of Schrödinger's cat. Macroscopic objects consisting of billions of atoms share collective degrees of freedom which may behave quantum mechanically, e.g. a sphere of micrometer diameter being in a spatial superposition between two different places. Such a quantum state of motion would allow to experimentally investigate decoherence, which describes the process of objects transitioning between states which are described by quantum mechanics to states which are described by Newtonian mechanics. Optomechanical structures pave a new way for testing the predictions of quantum mechanics and decoherence models and thereby might allow to answer some of the most fundamental questions in modern physics.

There is a broad range of experimental optomechanical systems which are almost equivalent in their description, but completely different in size, mass and frequency, ranging from attograms and gigahertz to kilograms and hertz. Cavity optomechanics was featured as the most recent milestone of photon history in nature photonics along well established concepts and technology like Quantum information, Bell inequalities and the laser.

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