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Inseparability criteria for bipartite quantum states
We provide necessary and sufficient conditions for the partial transposition
of bipartite harmonic quantum states to be nonnegative. The conditions are
formulated as an infinite series of inequalities for the moments of the state
under study. The violation of any inequality of this series is a sufficient
condition for entanglement. Previously known entanglement conditions are shown
to be special cases of our approach.Comment: 4 pages, no figures. Small misprints were correcte
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