Radiation from a uniformly accelerated particle detector: Energy, particles, and the quantum measurement process

We comment on the controversy whether a uniformly accelerated particle detector radiates. We stress the particular importance of the built-up correlations and of the quantum measurement process in this connection. We give the question the following form: We assume that the initial state of the quantum field is the Minkowski vacuum and that there is a uniformly accelerated two-level system which is initially in its ground state. What will in this case be found in the different regions of asymptotic future null infinity for the mean value of the field energy density on one hand and of the Minkowski particle number on the other if in the out region (a) no measurement is made on the two-level system, (b) the measurement finds the two-level system in its upper state, or (c) in its lower state? To obtain localized statements, we base the calculations on wave packet states. The different cases show essential differences