*Article* **Mixedness, Coherence and Entanglement in a Family of Three-Qubit States**

**Joanna K. Kalaga 1, Wiesław Leo ´nski 1,\*, Radosław Szcze¸ ´sniak <sup>2</sup> and Jan Peˇrina, Jr. <sup>3</sup>**


**Abstract:** We consider a family of states describing three-qubit systems. We derived formulas showing the relations between linear entropy and measures of coherence such as degree of coherence, firstand second-order correlation functions. We show that qubit–qubit states are strongly entangled when linear entropy reaches some range of values. For such states, we derived the conditions determining boundary values of linear entropy parametrized by measures of coherence.

**Keywords:** quantum entanglement; linear entropy; coherence; purity of states; concurrence; threequbit systems
