翻訳と辞書 Words near each other ・ Quantum concentration ・ Quantum configuration space ・ Quantum contextuality ・ Quantum Conundrum ・ Quantum convolutional code ・ Quantum Corporation ・ Quantum correlation ・ Quantum cosmology ・ Quantum coupling ・ Quantum critical point ・ Quantum cryptography ・ Quantum cylindrical quadrupole ・ Quantum Darwinism ・ Quantum decoherence ・ Quantum defect ・ Quantum depolarizing channel ・ Quantum Detectors ・ Quantum differential calculus ・ Quantum digital signature ・ Quantum dilogarithm ・ Quantum dimer models ・ Quantum discord ・ Quantum dissipation ・ Quantum dot ・ Quantum dot cellular automaton ・ Quantum dot display ・ Quantum dot laser ・ Quantum dot solar cell ・ Quantum dynamical semigroup ・ Quantum dynamics Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Quantum depolarizing channel ： ウィキペディア英語版 Quantum depolarizing channel A quantum depolarizing channel is a model for noise in quantum systems. The d-dimensional depolarizing channel can be viewed as a completely positive trace-preserving map $\backslash Delta\_\backslash lambda$, depending on one parameter $\backslash lambda$, which maps a state $\backslash rho$ onto a linear combination of itself and the maximally mixed state: :$\backslash Delta\_\backslash lambda(\backslash rho)=\backslash lambda\backslash rho+\backslash fracI$ The condition of complete positivity requires $\backslash lambda$ to satisfy the bounds: :$-\backslash frac\backslash le\backslash lambda\backslash le\; 1$ == Classical capacity == The HSW theorem states that the classical capacity of a quantum channel $\backslash Psi$ can be characterized as its regularized Holevo information: :$\backslash lim\_\backslash frac\backslash chi\backslash left(\backslash Psi^\backslash right)$ This quantity is difficult to compute and this reflects our ignorance on quantum channels. However, if the Holevo information is additive for a channel $\backslash Psi$, i.e., :$\backslash chi\backslash left(\backslash Psi\backslash otimes\backslash Psi\backslash right)=\backslash chi\backslash left(\backslash Psi\backslash right)+\backslash chi\backslash left(\backslash Psi\backslash right)$ Then we can get its classical capacity by computing the Holevo information of the channel. The additivity of Holevo information for all channels was a famous open conjecture in quantum information theory, but it is now known that this conjecture doesn't hold in general. This was proved by showing that the additivity of minimum output entropy for all channels doesn't hold, which is an equivalent conjecture. Nonetheless, the additivity of the Holevo information is shown to hold for the quantum depolarizing channel, and an outline of the proof is given below. As a consequence, entanglement across multiple uses of the channel cannot increase the classical capacity. In this sense, the channel behaves like a classical channel. To achieve the optimal rate of communication, it suffices to choose an orthonormal basis to encode the message, and perform measurements that project onto to the same basis at the receiving end. 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 depolarizing channel」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.