Maximally discordant mixed states of two qubits

Fernando Galve, Gian Luca Giorgi, and Roberta Zambrini
Phys. Rev. A 83, 012102 – Published 13 January 2011; Erratum Phys. Rev. A 83, 069905 (2011)

Abstract

We study the relative strength of classical and quantum correlations, as measured by discord, for two-qubit states. Quantum correlations appear only in the presence of classical correlations, while the reverse is not always true. We identify the family of states that maximize the discord for a given value of the classical correlations and show that the largest attainable discord for mixed states is greater than for pure states. The difference between discord and entanglement is emphasized by the remarkable fact that these states do not maximize entanglement and are, in some cases, even separable. Finally, by random generation of density matrices uniformly distributed over the whole Hilbert space, we quantify the frequency of the appearance of quantum and classical correlations for different ranks.

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  • Received 13 July 2010

DOI:https://doi.org/10.1103/PhysRevA.83.012102

© 2011 American Physical Society

Erratum

Erratum: Maximally discordant mixed states of two qubits [Phys. Rev. A 83, 012102 (2011)]

Fernando Galve, Gian Luca Giorgi, and Roberta Zambrini
Phys. Rev. A 83, 069905 (2011)

Authors & Affiliations

Fernando Galve, Gian Luca Giorgi, and Roberta Zambrini

  • IFISC (UIB-CSIC), Instituto de Física Interdisciplinar y Sistemas Complejos, UIB Campus, E-07122 Palma de Mallorca, Spain

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Issue

Vol. 83, Iss. 1 — January 2011

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