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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク quantum vortex ： ウィキペディア英語版 quantum vortex In physics, a quantum vortex is a topological defect exhibited in superfluids and superconductors. The existence of quantum vortices was predicted by Lars Onsager in 1947 in connection with superfluid helium. Onsager also pointed out that quantum vortices describe the circulation of superfluid and conjectured that their excitations are responsible for superfluid phase transitions. These ideas of Onsager were further developed by Richard Feynman in 1955 and in 1957 were applied to describe the magnetic phase diagram of type-II superconductors by Alexei Alexeyevich Abrikosov.〔 *Abrikosov, A. A. (1957) "( On the Magnetic properties of superconductors of the second group )", Sov.Phys.JETP 5:1174–1182 and Zh.Eksp.Teor.Fiz.32:1442-1452.〕 Quantum vortices are observed experimentally in Type-II superconductors, liquid helium, and atomic gases (see Bose–Einstein condensate). In a superfluid, a quantum vortex "carries" quantized angular momentum, thus allowing the superfluid to rotate; in a superconductor, the vortex carries quantized magnetic flux. ==Vortex in a superfluid== In a superfluid, a quantum vortex is a hole with the superfluid circulating around the vortex axis; the inside of the vortex may contain excited particles, air, vacuum, etc. The thickness of the vortex depends on a variety of factors; in liquid helium, the thickness is of the order of a few Angstroms. A superfluid has the special property of having phase, given by the wavefunction, and the velocity of the superfluid is proportional to the gradient of the phase. The circulation around any closed loop in the superfluid is zero if the region enclosed is simply connected. The superfluid is deemed irrotational, however, if the enclosed region actually contains a smaller region with an absence of superfluid, for example a rod through the superfluid or a vortex, when the circulation is: :$\backslash oint\_\; \backslash mathbf\backslash cdot\backslash ,d\backslash mathbf\; =\; \backslash frac\backslash oint\_\backslash nabla\backslash phi\backslash cdot\backslash ,d\backslash mathbf\; =\; \backslash frac\backslash Delta\backslash phi,$ where $\backslash hbar$ is Planck's constant divided by $2\backslash pi$, m is the mass of the superfluid particle, and $\backslash Delta\backslash phi$ is the phase difference around the vortex. Because the wavefunction must return to its same value after an integral number of turns around the vortex (similar to what is described in the Bohr model), then $\backslash Delta\backslash phi\; =\; 2\backslash pi\; n$, where n is an integer. Thus, the circulation is quantized: :$\backslash oint\_\; \backslash mathbf\backslash cdot\backslash ,d\backslash mathbf\; =\; \backslash fracn.$ 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「quantum vortex」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.