  Casimir-Polder interaction arises from the vacuum fluctuations of quantum
field that depend on spacetime curvature and thus is spacetime-dependent. Here
we show how to use the resonance Casimir-Polder interaction (RCPI) between two
entangled atoms to detect spacetime curvature. We find that the RCPI of two
static entangled atoms in the de Sitter-invariant vacuum depends on the de
Sitter spacetime curvature relevant to the temperature felt by the static
observer. It is characterized by a $1/L^2$ power law decay when beyond a
characteristic length scale associated to the breakdown of a local inertial
description of the two-atom system. However, the RCPI of the same setup
embedded in a thermal bath in the Minkowski universe is temperature-independent
and is always characterized by a $1/L$ power law decay. Therefore, although a
single static atom in the de Sitter-invariant vacuum responds as if it were
bathed in thermal radiation in a Minkowski universe, using the distinct
difference between RCPI of two entangled atoms one can in principle distinguish
these two universes.
