Journal ArticleDOI
Quantum discord for two-qubit systems
Reads0
Chats0
TLDR
In this paper, the quantum discord is defined as a measure of the discrepancy between two natural yet different quantum analogs of the classical mutual information, and quantifies quantumness of correlations in bipartite states.Abstract:
Quantum discord, as introduced by Olliver and Zurek [Phys. Rev. Lett. 88, 017901 (2001)], is a measure of the discrepancy between two natural yet different quantum analogs of the classical mutual information. This notion characterizes and quantifies quantumness of correlations in bipartite states from a measurement perspective, and is fundamentally different from the various entanglement measures in the entanglement vs separability paradigm. The phenomenon of nonzero quantum discord is a manifestation of quantum correlations due to noncommutativity rather than due to entanglement, and has interesting and significant applications in revealing the advantage of certain quantum tasks. We will evaluate analytically the quantum discord for a large family of two-qubit states, and make a comparative study of the relationships between classical and quantum correlations in terms of the quantum discord. We furthermore compare the quantum discord with the entanglement of formation, and illustrate that the latter may be larger than the former, although for separable states, the entanglement of formation always vanishes and thus is less than the quantum discord.read more
Citations
More filters
Journal ArticleDOI
The classical-quantum boundary for correlations: Discord and related measures
TL;DR: Different methods for quantifying the quantum and classical parts of correlations are among the more actively studied topics of quantum-information theory over the past decade as mentioned in this paper and different notions of classical and quantum correlations quantified by quantum discord and other related measures are reviewed.
Journal ArticleDOI
Quantum discord for two-qubit X states
TL;DR: In this article, the authors derived explicit expressions for quantum discord for a larger class of two-qubit states, namely, a seven-parameter family of so called X states that have been of interest in a variety of contexts in the field.
Journal ArticleDOI
Robustness of quantum discord to sudden death
TL;DR: In this paper, the dissipative dynamics of two-qubit quantum discord under Markovian environments were analyzed, and it was shown that quantum discord is more robust than the entanglement against decoherence.
Journal ArticleDOI
Classical correlation and quantum discord in critical systems
TL;DR: In this article, the behavior of quantum and classical pairwise correlations in critical systems, with the quantumness of the correlations measured by the quantum discord, is analyzed for general real density matrices displaying ${Z}_{2}$ symmetry.
Journal ArticleDOI
Quantum Correlations in Spin Chains at Finite Temperatures and Quantum Phase Transitions
TL;DR: It is shown that QD spotlight the critical points associated with quantum phase transitions (QPT) for this model even at finite T, which may have important implications for experimental characterization of QPTs when one is unable to reach temperatures below which a QPT can be seen.