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In the theory of quantum communication, the entanglement-assisted stabilizer formalism is a method for protecting quantum information with the help of entanglement shared between a sender and receiver before they transmit quantum data over a quantum communication channel. It extends the standard stabilizer formalism by including shared entanglement (Brun ''et al.'' 2006). The advantage of entanglement-assisted stabilizer codes is that the sender can exploit the error-correcting properties of an arbitrary set of Pauli operators. The sender's Pauli operators do not necessarily have to form an Abelian subgroup of the Pauli group over qubits. The sender can make clever use of her shared ebits so that the global stabilizer is Abelian and thus forms a valid quantum error-correcting code. == Definition == We review the construction of an entanglement-assisted code (Brun ''et al.'' 2006). Suppose that there is a nonabelian subgroup of size . Application of the fundamental theorem of symplectic geometry (Lemma 1 in the first external reference) states that there exists a minimal set of independent generators for with the following commutation relations: : : : : The decomposition of into the above minimal generating set determines that the code requires ancilla qubits and ebits. The code requires an ebit for every anticommuting pair in the minimal generating set. The simple reason for this requirement is that an ebit is a simultaneous -eigenstate of the Pauli operators . The second qubit in the ebit transforms the anticommuting pair into a commuting pair . The above decomposition also minimizes the number of ebits required for the code---it is an optimal decomposition. We can partition the nonabelian group into two subgroups: the isotropic subgroup and the entanglement subgroup . The isotropic subgroup is a commuting subgroup of and thus corresponds to ancilla qubits: :. The elements of the entanglement subgroup come in anticommuting pairs and thus correspond to ebits: :. 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「Entanglement-assisted stabilizer formalism」の詳細全文を読む スポンサード リンク
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