  We investigate the transition rates of uniformly accelerated two-level single
and entangled atomic systems in empty space as well as inside a cavity. We take
into account the interaction between the systems and a massless scalar field
from the viewpoint of an instantaneously inertial observer and a coaccelerated
observer, respectively. The upward transition occurs only due to the
acceleration of the atom. For the two-atom system, we consider that the system
is initially prepared in a generic pure entangled state. In the presence of a
cavity, we observe that for both the single and the two-atom cases, the upward
and downward transitions are occurred due to the acceleration of the atomic
systems. The transition rate manifests subtle features depending upon the
cavity and system parameters, as well as the initial entanglement. It is shown
that no transition occurs for a maximally entangled super-radiant initial
state, signifying that such entanglement in the accelerated two-atom system can
be preserved for quantum information procesing applications. Our analysis
comprehensively validates the equivalence between the effect of uniform
acceleration for an inertial observer and the effect of a thermal bath for a
coaccelerated observer, in free space as well as inside a cavity, if the
temperature of the thermal bath is equal to the Unruh temperature.
