von Neumann entropy S(ρ) = −Tr(ρ log ρ) on qubit channels: Shannon-quantum bridge

Von Neumann entropy on qubit channels. Setup: a noisy channel E acting on a qubit input ρ; von Neumann entropy S(ρ) = −Tr(ρ log ρ) quantifies the quantum information content. For a classical probability distribution {p, 1-p} S reduces to…