Quantum Entanglement for Atoms Coupling to Fluctuating Electromagnetic Field in the Cosmic String Spacetime

We investigate entanglement dynamics for two atoms coupling with fluctuating electromagnetic field in the cosmic string spacetime. We calculate the entanglement for different conditions. It is found that the entanglement behaviors are dependent on vacuum fluctuation, spacetime topology, two-atom separation and atomic polarization orientation. After a long time of evolution, entanglement would vanish, which means entanglement affected by electromagnetic fluctuation cannot maintain for a long time. For different spacetime topologies, entanglement presents different behaviors dependent on various parameters. When deficit angle parameter nu =1 and atom-string distance is toward infinity, the results in flat spacetime are recovered. When atoms keep close to the string, entanglement can be improved; specially, when two atoms locate on the string and have no polarization of axial direction, atoms are not affected by the electromagnetic fluctuation and entanglement can remain unchanged. When two-atom separation is relatively large, entanglement exhibits oscillation behavior as atom-string distance varies. This indicates that the existence of string profoundly modifies on the vacuum fluctuation and atom-field interaction. In addition, when two-atom separation is small, entanglement gains better improvement. Many parameters and conditions provide us with greater freedom to control the entanglement behaviors. In principle, this is useful to sense the cosmic string spacetime topology structure and property and discriminate different kinds of spacetime.