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Revision with unchanged content. The generation of entanglement in mesoscopic atomic ensembles is a challenging task for the fields of quantum information, quantum teleportation and precision measurements. A few subsets of such collective entangled states are analyzed in this work: spin squeezed states, Schrodinger cat states and Dicke states. Environmental decoherence is also considered, as it affects the quality of entanglement and a simple formalism for treating cooperative decay of coherence of multilevel atoms is developed and exemplified in a two qubit case.

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The author was born in 1978 in Piatra Neamt, Romania. He graduated with a BS degree in physics from the University of Bucharest, Romania in 2000 and with a Ph.D degree in physics from the University of Michigan, US in 2006. Currently he holds a postdoctoral researcher position at the University of Camerino, Italy.

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