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A symmetric, informationally complete, positive operator valued measure (SIC-POVM) is a special case of a generalized measurement on a Hilbert space, used in the field of quantum mechanics. A measurement of the prescribed form satisfies certain defining qualities that makes it an interesting candidate for a "standard quantum measurement," utilized in the study of foundational quantum mechanics. Furthermore, it has been shown that applications exist in quantum state tomography〔C. M. Caves, C. A. Fuchs, and R. Schack, “Unknown Quantum States: The Quantum de Finetti Representation,” J. Math. Phys. 43, 4537–4559 (2002).〕 and quantum cryptography.〔C. A. Fuchs and M. Sasaki, “Squeezing Quantum Information through a Classical Channel: Measuring the ‘Quantumness’ of a Set of Quantum States,” Quant. Info. Comp. 3, 377–404 (2003).〕 ==Definition== Due to the use of SIC-POVMs primarily in quantum mechanics, Dirac notation will be used to represent elements associated with the Hilbert space. In general, a POVM over a -dimensional Hilbert space is defined as a set of positive semidefinite operators on the Hilbert space that sum to the identity: : A SIC-POVM is more restrictive in that the operators must be subnormalized projectors related to one another such that they have the properties of symmetry and informational completeness. In this context informational completeness means that the probabilities of observing the various outcomes entirely determines any quantum state being measured by the scheme. This requires linearly independent operators. Symmetry means that the inner product of all pairs of subnormalized projectors is a constant: : The combination of symmetry and informational completeness means is composed entirely of operators of the form : where is a rank-one projector. 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「SIC-POVM」の詳細全文を読む スポンサード リンク
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