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J. Eisert and M. Cramer
Single-Copy Entanglement in Critical Spin Chains
Phys. Rev. A 72 (2005) 042112


    We consider the single-copy entanglement as a quantity to assess quantum correlations in the ground state in quantum many-body systems. We show for a large class of models that already on the level of single specimens of spin chains, criticality is accompanied with the possibility of distilling a maximally entangled state of arbitrary dimension from a sufficiently large block deterministically, with local operations and classical communication. These analytical results - which refine previous results on the divergence of block entropy as the rate at which EPR pairs can be distilled from many identically prepared chains - are made quantitative for general isotropic translationally invariant spin chains that can be mapped onto a quasi-free fermionic system, and for the anisotropic XY model. For the XX model, we provide the asymptotic scaling of ~(1/6)\log_2(L), and contrast it with the block entropy.

[ quant-ph/0506250 ]

file generated: 22 Nov 2006

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