The dynamical evolution of entanglement between two polarizable two-level atoms in weak interaction with electromagnetic vacuum fluctuations is investigated. We find that, for initial Bell state
ψ±, the decay rate of entanglement between atoms is just the superradiant spontaneous emission rate, which depends not only on the spontaneous emission rate of atom but also on the modulation of the spontaneous emission rate due to the presence of another atom. It is shown that, with the presence of a boundary, the entanglement between transversely polarizable atoms can be protected for a very long time. It is pointed out that when the two atoms in initial Bell state
ψ− are put close enough , the entanglement between them can also be protected.
The contribution of vacuum fluctuations and the radiation reaction to the energy-level shifts of a hydrogen atom, moving with uniform acceleration and interacting with the electromagnetic field, is considered. It is found that the reaction field contribution is not affected by the acceleration, whereas the vacuum fluctuations' contribution depends on the acceleration. The differences with previous results for an accelerated two-level atom interacting with a scalar field are discussed in detail; in particular, it is shown that the effect of electromagnetic vacuum fluctuations on atomic level shifts, contrarily to the scalar field case, is not totally equivalent to that of a thermal field. It is argued that this lack of equivalence should be observable.
We investigate the dynamics of multipartite quantum coherence (QC) for accelerated detector qubit coupled with fluctuating electromagnetic field by presence of a perfectly reflecting boundary. We firstly derive the master equation that the detector evolution obeys. We find that without boundary, QC declines under the impact of Unruh thermal effect and vacuum fluctuation. However, with a boundary, the degradation, floating and protection of QC are closely related to boundary effect, detector polarization and acceleration. The presence of boundary can effectively protect QC under the influence of vacuum fluctuation and Unruh thermal effect in some certain conditions and give us more freedom of adjusting the QC behaviors. Besides, it is shown that the QC of W state manifests better robustness than that of GHZ state under the influence of the vacuum fluctuation and acceleration.