Entanglement Quantification in Atomic Ensembles.

  title={Entanglement Quantification in Atomic Ensembles.},
  author={Matteo Fadel and Ayaka Usui and Marcus Huber and Nicolai Friis and Giuseppe Vitagliano},
  journal={Physical review letters},
  volume={127 1},
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… 

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