title: Detecting the Curvature of de Sitter Universe with Two Entangled Atoms.
abstract: 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/L2power 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.
authors.affiliation: Institute of Theoretical Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland.
authors.forename: Zehua
authors.initials: Z
authors.lastname: Tian
authors.affiliation: Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081, P. R. China.
authors.forename: Jieci
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081, P. R. China.
authors.forename: Jiliang
authors.initials: J
authors.lastname: Jing
authors.affiliation: Institute of Theoretical Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Dragan