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Coherent states have been introduced in a physical context, first as quasi-classical states in quantum mechanics, then as the backbone of quantum optics and they are described in that spirit in the article Coherent states (see also〔J-P. Gazeau,''Coherent States in Quantum Physics'', Wiley-VCH, Berlin, 2009.〕). However, they have generated a huge variety of generalizations, which have led to a tremendous literature in mathematical physics. In this article, we sketch the main directions of research on this line. For further details, we refer to several existing surveys .〔S.T. Ali, J-P. Antoine, J-P. Gazeau, and U.A. Mueller, Coherent states and their generalizations: A mathematical overview, ''Reviews in Mathematical Physics'' 7 (1995) 1013-1104.〕〔S.T. Ali, J-P. Antoine, and J-P. Gazeau, ''Coherent States, Wavelets and Their Generalizations'', Springer-Verlag, New York, Berlin, Heidelberg, 2000.〕〔S.T. Ali, Coherent States, ''Encyclopedia of Mathematical Physics'', pp. 537-545; Elsevier, Amsterdam, 2006.〕 == A general definition == Let be a complex, separable Hilbert space, a locally compact space and a measure on . For each in , denote a vector in . Assume that this set of vectors possesses the following properties: # The mapping is weakly continuous, i.e., for each vector in , the function is continuous (in the topology of ). # The resolution of the identity : holds in the weak sense on the Hilbert space , i.e., for any two vectors in , the following equality holds: : A set of vectors satisfying the two properties above is called a family of ''generalized coherent states''. In order to recover the previous definition (given in the article Coherent state) of canonical or standard coherent states (CCS), it suffices to take , the complex plane, and Sometimes the resolution of the identity condition is replaced by a weaker condition, with the vectors simply forming a total set in and the functions , as runs through , forming a ''reproducing kernel Hilbert space''. The objective in both cases is to ensure that an arbitrary vector be expressible as a linear (integral) combination of these vectors. Indeed, the resolution of the identity immediately implies that : where . These vectors are square integrable, continuous functions on and satisfy the ''reproducing property'' : where is the reproducing kernel, which satisfies the following properties : : 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「Coherent states in mathematical physics」の詳細全文を読む スポンサード リンク
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