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Title: Comparison of the attempts of quantum discord and quantum entanglement to capture quantum correlations

Abstract

Measurements of quantum systems disturb their states. To quantify this nonclassical characteristic, Zurek and Ollivier [Phys. Rev. Lett. 88, 017901 (2001)] introduced the quantum discord, a quantum correlation that can be nonzero even when entanglement in the system is zero. Discord has aroused great interest as a resource that is more robust against the effects of decoherence and offers the exponential speed-up of certain computational algorithms. Here, we study general two-level bipartite systems and give general results on the relationship between discord, entanglement, and linear entropy. We also identify the states for which discord takes a maximal value for a given entropy or entanglement, thus placing strong bounds on entanglement-discord and entropy-discord relations. We find out that although discord and entanglement are identical for pure states, they differ when generalized to mixed states as a result of the difference in the method of generalization.

Authors:
;  [1]
  1. Department of Physics and Centre for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 1A7 (Canada)
Publication Date:
OSTI Identifier:
21537374
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 83; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevA.83.032101; (c) 2011 American Institute of Physics; Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALGORITHMS; CAPTURE; ENTROPY; MIXED STATES; PURE STATES; QUANTUM ENTANGLEMENT; MATHEMATICAL LOGIC; PHYSICAL PROPERTIES; QUANTUM STATES; THERMODYNAMIC PROPERTIES

Citation Formats

Qasimi, Asma Al-, and James, Daniel F. V. Comparison of the attempts of quantum discord and quantum entanglement to capture quantum correlations. United States: N. p., 2011. Web. doi:10.1103/PHYSREVA.83.032101.
Qasimi, Asma Al-, & James, Daniel F. V. Comparison of the attempts of quantum discord and quantum entanglement to capture quantum correlations. United States. doi:10.1103/PHYSREVA.83.032101.
Qasimi, Asma Al-, and James, Daniel F. V. Tue . "Comparison of the attempts of quantum discord and quantum entanglement to capture quantum correlations". United States. doi:10.1103/PHYSREVA.83.032101.
@article{osti_21537374,
title = {Comparison of the attempts of quantum discord and quantum entanglement to capture quantum correlations},
author = {Qasimi, Asma Al- and James, Daniel F. V.},
abstractNote = {Measurements of quantum systems disturb their states. To quantify this nonclassical characteristic, Zurek and Ollivier [Phys. Rev. Lett. 88, 017901 (2001)] introduced the quantum discord, a quantum correlation that can be nonzero even when entanglement in the system is zero. Discord has aroused great interest as a resource that is more robust against the effects of decoherence and offers the exponential speed-up of certain computational algorithms. Here, we study general two-level bipartite systems and give general results on the relationship between discord, entanglement, and linear entropy. We also identify the states for which discord takes a maximal value for a given entropy or entanglement, thus placing strong bounds on entanglement-discord and entropy-discord relations. We find out that although discord and entanglement are identical for pure states, they differ when generalized to mixed states as a result of the difference in the method of generalization.},
doi = {10.1103/PHYSREVA.83.032101},
journal = {Physical Review. A},
issn = {1050-2947},
number = 3,
volume = 83,
place = {United States},
year = {2011},
month = {3}
}