Oscar Rosas-Ortiz
Optimized two-qubit systems
We investigate the entanglement properties of two-qubit sys-
tems by using the minimum of essential parameters. The idea
is to construct density operators whose reduced one-qubit states
share the same entropy, regardless of whether the state of the
entire system is pure or mixed. We show that the parameters so found define a convex set S that can be divided in subsets whose
points are linked to separable states and regions where entangle-
ment may be found. Geometrically, S is nothing more than a right-triangle in RxR.
