Maximally discordant mixed states of two qubits

Journal Article · Sat Jan 15 00:00:00 EST 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.012102· OSTI ID:21529028

Galve, Fernando; Giorgi, Gian Luca; Zambrini, Roberta ^[1]

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1. IFISC (UIB-CSIC), Instituto de Fisica Interdisciplinar y Sistemas Complejos, UIB Campus, E-07122 Palma de Mallorca (Spain)

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.

• OSTI ID: 21529028
• Journal Information: Physical Review. A, Vol. 83, Issue 1; Other Information: DOI: 10.1103/PhysRevA.83.012102; (c) 2011 American Institute of Physics; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CORRELATIONS
DENSITY MATRIX
HILBERT SPACE
MIXED STATES
PURE STATES
QUANTUM ENTANGLEMENT
QUBITS
RANDOMNESS
BANACH SPACE
INFORMATION
MATHEMATICAL SPACE
MATRICES
QUANTUM INFORMATION
QUANTUM STATES
SPACE