Entanglement Quantification in Atomic Ensembles
Entanglement Quantification in Atomic Ensembles
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DOI：
10.1103/physrevlett.127.010401
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发表时间：
2021-06-29
影响因子：
8.6
通讯作者：
Vitagliano, Giuseppe
中科院分区：
文献类型：
--
作者：
Fadel, Matteo;Usui, Ayaka;Vitagliano, Giuseppe
纠缠测量量化了量子系统中存在的非经典关联，但计算起来可能非常困难，当有关其状态的信息有限时，就更难计算了。在这里，我们考虑了广泛的基于任意算符的方差的纠缠判据，并解析地推导了这些判据为两个相关的纠缠度量提供的下界：最佳可分近似和广义稳健性。这产生了一种在实际实验情况下量化纠缠的实用方法，特别是当只有几个简单可观测到的测量数据时。作为该方法的一个具体应用，我们通过给出最佳可分离近似的下界和仅从集体自旋算符的一阶和二阶矩测量得到的广义稳健性来量化类似于500个原子的自旋压缩玻色-爱因斯坦凝聚体中的二体和多体纠缠。
Entanglement measures quantify nonclassical correlations present in a quantum system, but can be extremely difficult to calculate, even more so, when information on its state is limited. Here, we consider broad families of entanglement criteria that are based on variances of arbitrary operators and analytically derive the lower bounds these criteria provide for two relevant entanglement measures: the best separable approximation and the generalized robustness. This yields a practical method for quantifying entanglement in realistic experimental situations, in particular, when only few measurements of simple observables are available. As a concrete application of this method, we quantify bipartite and multipartite entanglement in spin-squeezed Bose-Einstein condensates of similar to 500 atoms, by lower bounding the best separable approximation and the generalized robustness only from measurements of first and second moments of the collective spin operator.