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In quantum information theory, the idea of a typical subspace plays an important role in the proofs of many coding theorems (the most prominent example being Schumacher compression). Its role is analogous to that of the typical set in classical information theory. == Unconditional Quantum Typicality == Consider a density operator with the following spectral decomposition: : The weakly typical subspace is defined as the span of all vectors such that the sample entropy of their classical label is close to the true entropy of the distribution : : where : : The projector onto the typical subspace of is defined as : where we have "overloaded" the symbol The three important properties of the typical projector are as follows: : : : where the first property holds for arbitrary and sufficiently large . 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「Typical subspace」の詳細全文を読む スポンサード リンク
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