Quantum Computing, Qubit, Hilbert Space.
of two or more particles are entangled with each other. A state ρ ∈ D (HA ⊗HB) in a composite system HA ⊗HB, where HA HB are sub systems is said to be separable, if there exist states ρA j ∈ D(HA )and ρB j ∈ D(HB), j ∈ I and a positive real numbers pj satisfying ∑ pj = 1, such that ρ = ∑ pj ρA j