We derive the structure of the density matrix for two Unruh-DeWitt detectors coupled to a massless scalar field to all orders of perturbation theory, in spacetimes admitting a well-defined Wightman function. Calculating all of its leading terms enables us to fully characterize observable correlations, entanglement, and quantum discord. We apply these results to study detector responses in two locally flat topologically nontrivial spacetimes constructed from identifications of Minkowski space. We demonstrate how local statistics and detector-detector correlations depend on the global spacetime structure. In particular, we show that if the spacetime has a preferred direction, this direction may be inferred from the dependence of correlations between the two detectors on their orientation. While using such measurements to distinguish spacetimes with identical local geometry is apparently impractical, this effect points to fundamental connections between quantum field correlations and the structure of spacetime. This relationship may also be relevant in the phenomenology of the early Universe.
|Number of pages||13|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|Publication status||Published - 1 Feb 2016|