科研之友
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摘要
We introduce two tangle-based four-party entanglement measures t(1) and t(2), and two negativity-based measures n(1) and n(2), which are derived from the monogamy relations. These measures are computed for three four-qubit maximally entangled and W states explicitly. We also compute these measures for the rank-2 mixture rho(4) = p|GHZ4 > < GHZ(4)| + (1 - p)|W-4 > < W-4| by finding the corresponding optimal decompositions. It turns out that t(1)(rho(4)) is trivial and the corresponding optimal decomposition is equal to the spectral decomposition. Probably, this triviality is a sign of the fact that the corresponding monogamy inequality is not sufficiently tight. We fail to compute t(2)(rho(4)) due to the difficulty in the calculation of the residual entanglement. The negativity-based measures n(1)(rho(4)) and n(2)(rho(4)) are explicitly computed and the corresponding optimal decompositions are also derived explicitly.
- 出版日期2016-10-20
