Manuscript Em04-A@2 · Em04-A-v2.tex · section · f5b28abc

Two-site concurrence

Exact diagnostic and entanglement identities › Two-site concurrence · lines 400–413

For a two-qubit density matrix $ω$ , let

ω = (Y \otimes Y) ω (Y \otimes Y) .

The concurrence is

C (ω) = max {0, λ_{1} - λ_{2} - λ_{3} - λ_{4}},

where the decreasing $λ_{ℓ}$ are the nonnegative square roots of the eigenvalues of $ω ω$ Wootters.

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