量子Swapping网络中非局域性度量的上界的优化

Refining upper bounds of the measurement-induced nonbilocal correlation in the Swapping experiment

测量诱导的非双局域关联是一种通过对多体量子系统状态进行局部测量来量化Swapping网络中非局域性的度量。在纯态情形这类度量具有解析的计算公式,但对于混合态情形无法精确计算,只能对其上界进行估计。该文研究一类特殊的混合态,即边缘态ρ_(BC)具有直积态ρ_(BC)=ρ_(B)■ρ_(C)形式,其中ρ_(B)是非简并且ρ_(C)是简并的情况,得到了该类混合态测量诱导的非双局域关联上界更精细的计算公式。

Measurement-induced nonbilocal correlation is a measure which quantifies the nonlocality in the entanglement-swapping experiment under local measurements.The measure can be calculated for the pure state,however not for the mixed state.It is obtained that a refined upper bound of the measurement-induced nonbilocal correlation for a special class of mixed states,that is,the marginal stateρBC of every state in this class is a product stateρ_(BC)=ρ_(B)■ρ_(C),ρ_(B) is non-degenerate andρ_(C) is degenerate.