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Cavity opto-mechanics 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). 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''〔http://www.nature.com/milestones/milephotons/full/milephotons23.html〕 in nature photonics along well established concepts and technology like Quantum information, Bell inequalities and the laser. == Concepts of cavity opto-mechanics == According to the quantum theory of light, every photon with wave number carries a momentum with Planck's constant . This means that a photon which is reflected off a mirror surface transfers a momentum onto the mirror, since the net momentum has to be conserved. This effect is extremely small and can not be observed on most every-day objects, however it becomes more significant when the mass of the mirror is very small. Photons can be prepared in quantum (non-classical) states. If one assumes that quantum mechanics also describes the physics of the motion of a small mirror, it should be possible to use quantum states of photons to create quantum states of mirrors. Compared to most "typical" quantum objects like photons, electrons, atoms and small molecules, even a nanogram mirror which can just be seen under a microscope is larger by many orders of magnitude. This makes optomechanical structures the closest experimental neighbours to the quantum cat in Schrödinger's Gedankenexperiment. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cavity optomechanics」の詳細全文を読む スポンサード リンク
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