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论文类型：期刊论文

第一作者：Yu, Chang-shui

通讯作者：Yu, CS (reprint author), Dalian Univ Technol, Sch Phys & Optoelect Technol, Dalian 116024, Peoples R China.

合写作者：Li, C.,Song, He-shan

发表时间：2008-01-01

发表刊物：PHYSICAL REVIEW A

收录刊物：SCIE、EI

卷号：77

期号：1

ISSN号：1050-2947

摘要：We show that bipartite concurrence for rank-2 mixed states of qubits is written by an observable which can be exactly and directly measurable in experiment by local projective measurements, provided that four copies of the composite quantum system are available. In addition, for a tripartite quantum pure state of qubits, the 3-tangle is also shown to be measurable only by projective measurements on the reduced density matrices of a pair of qubits conditioned on four copies of the state.