Investigation of the Relationship of the Degree of Mixedness and Entanglement of the Bipartite Spin Coherent States

In this work, superposition of spin coherent states composed of two qubits is formed and by calculating the geometric measure of mixing of the system introduced in this work, the degree of mixedness of the studied state is investigated. In the following, the changes in the entanglement of the introduced state are studied by using the negativity measure. Finally, by drawing the appropriate plots, according to the influential parameters in this system, we examine the maximum and the minimum of the changes in the mixedness and entanglement and also their relationship to the mixed system consisting of two-qubit spin coherent states. It was observed that for maximizing α, when the changes of parameters indicate the purity of the state, the entanglement of the system reaches its maximum value for two-qubit systems. Also, for all values of coherence parameter, the entanglement decreases when mixedness of the system increases.