Analytical Expression of Quantum Discord for Rank-2 Two-qubit States

Xue-Na Zhu, Xianqing Li-Jost, and Shao-Ming Fei

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Submission date: 20. Aug. 2018
Pages: 9
published in: Quantum information processing, 17 (2018) 9, art-no. 234 
DOI number (of the published article): 10.1007/s11128-018-2007-6
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Abstract:
Quantum correlations characterized by quantum entanglement and quantum discord play important roles in many quantum information processing. We study the relations among the entanglement of formation, concurrence, tangle, linear entropy based classical correlation and von Neumann entropy based classical correlation . We present analytical formulae of linear entropy based classical correlation for arbitrary d ⊗ 2 quantum states and von Neumann entropy based classical correlation for arbitrary 2 ⊗ 2 rank-2 quantum states. From the von Neumann entropy based classical correlation, we derive an explicit formula of quantum discord for arbitrary rank-2 two-qubit quantum states.