Search

We show that it is possible to still use semiclassical gravity together with quantum field theory beyond the regimes where the field state is coherent. In particular, we identify families of cat states (superposition of almost-distinguishable coherent states that have very non-classical features) for which the gravitational backreaction can be modeled by semiclassical gravity., Comment: 9 pages, 1 Appendix. RevTeX 4.2

We study the finite time response of an Unruh-DeWitt particle detector described by a qubit (two-level system) moving with uniform constant acceleration in maximally symmetric spacetimes. The $D$ dimensional massless fermionic response function in de Sitter (dS) background is found to be identical to that of a detector linearly coupled to a massless scalar field in $2D$ dimensional dS background. Furthermore, we visit the status of Huygen's principle in the Unruh radiation observed by the detector.

We have investigated the Unruh effect in Anti de-Sitter (AdS) spacetime by examining the response function of an Unruh-DeWitt particle detector with uniform constant acceleration. An exact expression of the detector response function for the scalar field has been obtained with different levels of non-linearity in even dimensional AdS spacetime. We also showed how the response of the accelerated Unruh detector coupled quadratically to massless Dirac field in $D$ dimensional $(D \geq 2)$ AdS spacetime is proportional to that of a detector linearly coupled to a massless scalar field in $2D$ dimensional AdS spacetime. Here, the fermionic and scalar matter field is coupled minimally and conformally to the background AdS metric, respectively. Finally, we discuss about the extension of the results for more general stationary motion., Comment: 35 pages, 6 figures