Lower Bound of Concurrence for Qubit Systems
Xue-Na Zhu and Shao-Ming Fei
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Submission date: 10. Feb. 2014
published in: Quantum information processing, 13 (2014) 3, p. 815-823
DOI number (of the published article): 10.1007/s11128-013-0693-7
PACS-Numbers: 03.67.-a, 02.20.Hj, 03.65.-w
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We study the concurrence of four-qubit quantum states and provide analytical lower bounds of concurrence in terms of the monogamy inequality of concurrence for qubit systems. It is shown that these lower bounds are able to improve the existing bounds and detect entanglement better. The approach is generalized to arbitrary qubit systems.