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APS » Journals » Physical Review Letters » Entanglement of subspaces in terms of entanglement of superpositions

December 2007, to be published in Physical Review A

Entanglement of subspaces in terms of entanglement of superpositions
Gilad Gour and Aidan Roy

We investigate upper and lower bounds on the entropy of entanglement of a superposition of bipartite states as a function of the individual states in the superposition. In particular, we extend the results in [G. Gour, arxiv.org:0707.1521 (2007)] to superpositions of several states rather than just two. We then investigate the entanglement in a subspace as a function of its basis states: we find upper bounds for the largest entanglement in a subspace and demonstrate that no such lower bound for the smallest entanglement exists. Finally, we consider entanglement of superpositions using measures of entanglement other than the entropy of entanglement.

© 2008 The American Physical Society.