Separability and the stella octangula
نویسنده
چکیده
A geometrical picture of separability of 2× 2 composite quantum systems, showing the region of separable density matrices in the space of hermitian matrices, is given. It rests on the criterion of separability given by Peres [1], and it is an extension of the “Horodecki diagram” [2] and the “stella octangula” described by Aravind [3]. An illustration of which composite quantum states that are separable is desirable. The separable states is a convex set in the space of hermitian matrices, and a nice geometrical picture of this for Bell-diagonal 2×2 systems is given by the “Horodecki diagram” [2]. Here we will extend this idea to non-Bell-diagonal mixtures. A composite quantum system of two subsystems, described by a density matrix ρ in the Hilbert-Schmidt space H⊗H, is separable if it can be written as a statistical mixture of product states,
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