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Accueil > Séminaires > Archive des séminaires d’Utinam > 2015

Dominique Spehner

Geometric quantum discords

mercredi 17 juin 2015, 14h00

salle de conférences de l’observatoire

Dominique Spehner, Laboratoire de Physique et Modélisation des Milieux Condensés, Université Grenoble-Alpes

Résumé :

The geometric quantum discord is a measure of quantum correlations which has similar properties than the quantum discord proposed by Ollivier and Zurek and Henderson and Vedral to quantify the degree of non-classicality in a bipartite system. It is defined as the minimal distance of the system state to a classical state with respect to one subsystem, that is, to a state with zero quantum discord. It is also of interest for applications in irreversible dynamical processes to determine the closest classical state(s) to a given state.
We will discuss in this talk some results on the geometric discord and closest classical states when the distance on the set of quantum states is either the Bures or the quantum Hellinger distance. For pure states, the corresponding discords reduce to known entanglement-monotone measures. For mixed states, the Bures geometric discord coincides with the optimal success probability of an ambiguous quantum state discrimination task. We will show some general relations and inequalities between the discords for the Bures, quantum Hellinger, and Hilbert-Schmidt distances and argue that analytical explicit expressions can be obtained at least when the measured subsystem is a qubit.