Abstract : We show that the quantum Fisher information provides a sufficient condition to recognize multi-particle entanglement in a N qubit state. The same criterion gives a necessary and sufficient condition for sub shot-noise phase sensitivity in the estimation of a collective rotation angle θ . The analysis therefore singles out the class of entangled states which are {\it useful} to overcome classical phase sensitivity in metrology and sensors. We finally study the creation of useful entangled states by the non-linear dynamical evolution of two decoupled Bose-Einstein condensates or trapped ions.
https://hal-iogs.archives-ouvertes.fr/hal-00626569
Contributeur : Marie-Laure Edwards
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Soumis le : jeudi 31 mars 2016 - 16:23:19
Dernière modification le : jeudi 11 janvier 2018 - 06:26:06
Document(s) archivé(s) le : lundi 14 novembre 2016 - 11:35:48
