An Entanglement Measure
Let a composite quantum system have state space
and ρ be a density matrix acting on H.
The relative entropy of entanglement of ρ is defined by
where the minimum is taken over the family of separable states. A physical interpretation of the quantity is the optimal distinguishability of the state ρ from separable states.
Clearly, when ρ is not entangled
by Klein's inequality.
Read more about this topic: Quantum Relative Entropy
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