Problem of quantifying quantum correlations with non-commutative discord

MAJTEY, A.P.; BUSSANDRI, D.G.; OSÁN, T.M.; LAMBERTI, P.W.; VALDÉS-HERNÁNDEZ, A.

QUANTUM INFORMATION PROCESSING

SPRINGER

Año: 2017 vol. 16

1570-0755

n this work we analyze a non-commutativity measure of quantum correlations recently proposed by Guo (Sci Rep 6:25241, 2016). By resorting to a systematic survey of a two-qubit system, we detected an undesirable behavior of such a measure related to its representation-dependence. In the case of pure states, this dependence manifests as a non-satisfactory entanglement measure whenever a representation other than the Schmidt?s is used. In order to avoid this basis-dependence feature, we argue that a minimization procedure over the set of all possible representations of the quantum state is required. In the case of pure states, this minimization can be analytically performed and the optimal basis turns out to be that of Schmidt?s. In addition, the resulting measure inherits the main properties of Guo?s measure and, unlike the latter, it reduces to a legitimate entanglement measure in the case of pure states. Some examples involving general mixed states are also analyzed considering such a