Quantitative entanglement witnesses allow one to bound the entanglement present in a system by acquiring a single expectation value. In this paper, we analyze a special class of such observables which are associated with (generalized) Werner and isotropic states. Their optimal bounding functions can be easily derived by exploiting known results on twirling transformations. By focusing on an explicit local decomposition for these observables, we then show how simple classical post-processing of the measured data can tighten the entanglement bounds. Quantum optics implementations based on hyperentanglement generation schemes are analyzed.
Quantitative entanglement witnesses of isotropic and Werner classes via local measurements
FAZIO, ROSARIO;GIOVANNETTI, VITTORIO
2011
Abstract
Quantitative entanglement witnesses allow one to bound the entanglement present in a system by acquiring a single expectation value. In this paper, we analyze a special class of such observables which are associated with (generalized) Werner and isotropic states. Their optimal bounding functions can be easily derived by exploiting known results on twirling transformations. By focusing on an explicit local decomposition for these observables, we then show how simple classical post-processing of the measured data can tighten the entanglement bounds. Quantum optics implementations based on hyperentanglement generation schemes are analyzed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.