W-态的纠缠鲁棒性和广义纠缠鲁棒性

The robustness of entanglement and the generalized robustness of entanglement of W-states

研究了W-态的纠缠鲁棒性和广义纠缠鲁棒性。首先,分别找到了它的纠缠鲁棒性和广义纠缠鲁棒性的一个上界和一个下界,并给出了上界和下界相等的条件,进而,在该条件下,得到了W-态的纠缠鲁棒性和广义纠缠鲁棒性。作为特例,证明了W_λ-态的纠缠鲁棒性和广义鲁棒性是相等的,并分别找到了它的最优态和广义最优态。最后,证明了广义纠缠鲁棒性作为量子态集合是下半连续的。

The robustness of entanglement（R·E）and the generalized robustness of entanglement（GR·E）of the W-states are discussed.First,upper and lower bounds for R·E and GR·E are found,respectively,and some conditions for the upper bound and the lower bound to be equal are obtained.R·E and GR·E of W-states are then computed under the obtained conditions.As a special case of W-states,it is proved that R·E and GR·E of a Wλ-state are equal and the related optimal state,generalized optimal state are also found,respectively.In the end,it is proved that the GR·E function is lower semi-continuous on the set of all bipartite states.