Quantifying the non-classical correlation of a two-atom system nonlinearly interacting with a coherent cavity: local quantum Fisher information and Bures distance entanglement

The sensitivity of local quantum Fisher information and the Bures distance entanglement as quantifiers of the non-classical correlations, is examined for a atomic system interacting nonlinearly with a single cavity field. The general behavior shows that, the amount of the nonclassical correlation between the atomic subsystems that depicted by the local quantum Fisher information is larger than that detected by Bures distance entanglement. It is shown that, the long-lived non-classical correlations between the atomic subsystems is depicted in the presence of the intrinsic coherence and enhanced by switching on the dipole-dipole interaction. However, the upper bounds of these correlations decreases if the field is initially prepared in an even coherent state. Although the long-lived behavior of these correlations disappear at large values of the mean photon numbers, but the maximum and minimum bounds of these correlations are enhanced.)