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arXiv:quant-ph/0302144 · Europhysics Letters (EPL)

Entanglement of 2× K quantum systems

Artur Łoziński, Andreas Buchleitner, Karol Życzkowski, Thomas Wellens

Published Apr 1, 2003• 30 citations
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Abstract

We derive an analytical expression for the lower bound of the concurrence of mixed quantum states of composite 2 × K systems. In contrast to other, implicitly defined entanglement measures, the numerical evaluation of our bound is straightforward. We explicitly evaluate its tightness for general mixed states of 2 × 3 systems, and identify a large class of states where our expression gives the exact value of the concurrence.

DOI
10.1209/epl/i2003-00342-y

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We derive an analytical expression for the lower bound of the concurrence of mixed quantum states of composite 2 × K systems. In contrast to other, implicitly defined entanglement measures, the numerical evaluation of our bound is straightforward. We explicitly evaluate its tightness for general mixed states of 2 × 3 systems, and identify a large class of states where our expression gives the exact value of the concurrence.
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