Quantum Information Processing

, Volume 14, Issue 6, pp 1947–1958 | Cite as

Analytical solutions and criteria for the quantum discord of two-qubit X-states

  • A. Maldonado-Trapp
  • Anzi Hu
  • Luis Roa


Except for a few special states, computing quantum discord remains a complicated optimization process. In this paper, we present analytical solutions for computing quantum discord of the most general class of \(X\)-states and the criteria for each analytical solution to be valid. We discuss parameter regions that correspond to different analytical solutions and explain the underlying reasons for such structure to exist. We apply our formalism to study both arbitrary \(X\)-states and \(X\)-states with certain symmetries. We find that our analytical formalism is in excellent agreement with numerical calculation of quantum discord in both cases.


Quantum discord Quantum information Quantum correlations X-states 



A. M. T acknowledges the financial support of CONICYT.


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© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Departamento de FísicaUniversidad de ConcepciónConcepciónChile
  2. 2.Department of PhysicsAmerican UniversityWashingtonUSA

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