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Separability and entanglement in 2xN composite quantum systems

M. Lewenstein·J. I. Cirac·S. Karnas
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Abstract

We show that all density operators of 2$\times N$--dimensional quantum systems that remain invariant after partial transposition with respect to the first system are separable. Based on this criterion, we derive a sufficient separability condition for general density operators in such quantum systems. We also give a simple proof of the separability criterion in $2\times 2$--dimensional systems [A. Peres, Phys. Rev. Lett {\bf 77}, 1413 (1996)]

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M. Lewenstein, J. I. Cirac, S. Karnas. 1999-03-03. Separability and entanglement in 2xN composite quantum systems. https://arxiv.org/abs/quant-ph/9903012

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