Entanglement distribution revealed by macroscopic observations

Author(s): J. Kofler, Č. Brukner

Journal: Physical Review A

Volume: 74

Page(s): 050304(R)

Year: 2006

DOI Number: 10.1103/PhysRevA.74.050304

Link: Link to publication


What can we learn about entanglement between individual particles in macroscopic samples by observing only the collective properties of the ensembles? Using only a few experimentally feasible collective properties, we establish an entanglement measure between two samples of spin-1/2 particles (as representatives of two-dimensional quantum systems). This is a tight lower bound for the average entanglement between all pairs of spins in general and is equal to the average entanglement for a certain class of systems. We compute the entanglement measures for explicit examples and show how to generalize the method to more than two samples and multipartite entanglement.

Note: http://arxiv.org/abs/quant-ph/0603208

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