The role of dipole-dipole interaction and the scattering strength in entanglement dynamics between atoms surrounding a microtoroidal cavity

Abstract

In this work we have shown that the dipole-dipole interaction and the scattering strength have a role in entanglement dynamics between two and three two-level atoms with dipole-dipole interaction coupled to a whispering-gallery-mode (WGM) microtoroidal cavity for a given initial state. For this purpose, we present two different cases where the two atoms are coupled symmetrically or asymmetrically to the two WGMs through evanescent fields. Considering the symmetric regime and two types of initial states for the atoms, we have shown that for the initial entangled state, the sudden death and birth, as well as the freezing of the entanglement, can be obtained by adjusting both the scattering strength between modes and the dipole-dipole interaction, in contraposition to the product initial state. Moreover, we have noted that the atomic entanglement generation is more susceptible to the scattering strength variation between the modes than to the dipole-dipole interaction. In addition, for the asymmetric regime, the entanglement generation is strongly dependent on the atomic location and the scattering strength. Similar results are obtained for the case of three atoms coupled to a microtoroidal cavity, even in the presence of losses.