We discuss the paradigmatic bipartite spin-12 system having the probabilities (1+3x)/4 of being in the Einstein–Podolsky–Rosen fully entangled state |Ψ−〉≡1/2(|↑〉A|↓〉B−|↓〉A|↑〉B) and 3(1−x)/4 of being orthogonal. This system is known to be separable if and only if...

We investigate the changes in the entanglement of formation ΔE produced by quantum logical gates acting on composite quantum systems. We consider two-qubit, three-qubit, and two-qutrit systems. We prove that the ΔE-distributions generated by different quantum gates that can be obtained from...

We consider the change of entanglement of formation ΔE produced by the Hadamard-CNOT circuit on a general (pure or mixed) state ρ describing a system of two qubits. We study numerically the probabilities of obtaining different values of ΔE, assuming that the initial state is randomly...