Information Quantities
S(A)--
S(B)--
S(A,B)--
I(A:B) total--
Entanglement E--
Classical J--
Discord δ--
Discord δ = I(A:B) − J(A:B)
Captures non-classical correlations beyond entanglement.
Separable states can have δ > 0.
I(A:B) = S(A) + S(B) − S(A,B)