Pairwise Quantum Correlations for Superpositions of Dicke States
  Pairwise correlation is really an important property for multi-qubit states. For the two-qubit X states extracted from Dicke states and their superposition states, we obtain a compact expression of the quantum discord by numerical check. We then apply the expression to discuss the quantum correlation of the reduced two-qubit states of Dicke states and their superpositions, and the results are compared with those obtained by entanglement of formation, which is a quantum entanglement measure. 
Zhengjun Xi, Heng-Na Xiong, Yongming Li, and Xiaoguang Wang
quant-ph