Higher-order EPR correlations and inseparability conditions for continuous variables
Abstract
We derive two types of sets of higher-order conditions for bipartite entanglement in terms of continuous variables. One corresponds to an extension of the well-known Duan inequalities from second to higher moments describing a kind of higher-order Einstein-Podolsky-Rosen (EPR) correlations. Only the second type, however, expressed by powers of the mode operators leads to tight conditions with a hierarchical structure. We start with a minimization problem for the single-partite case and, using the results obtained, establish relevant inequalities for higher-order moments satisfied by all bipartite separable states. A certain fourth-order condition cannot be violated by any Gaussian state and we present non-Gaussian states whose entanglement is detected by that condition. Violations of all our conditions are provided, so they can all be used as entanglement tests.
Cite
@article{arxiv.1511.08444,
title = {Higher-order EPR correlations and inseparability conditions for continuous variables},
author = {E. Shchukin and P. van Loock},
journal= {arXiv preprint arXiv:1511.08444},
year = {2016}
}
Comments
16pages, 4 figures