title: Quasiresonant van der Waals Interaction between Nonidentical Atoms.
abstract: We present a time-dependent quantum calculation of the van der Waals interaction between a pair of dissimilar atoms, one of which is initially excited while the other one is in its ground state. For small detuning, the interaction is predominantly mediated at all distances by the exchange of doubly resonant photons between the two atoms. We find that it presents both temporal and spatial oscillations. Spatially oscillating terms depend on the resonant frequencies of both atoms, while the frequency of the time oscillations is given by their detuning. We analyze the physical content of our findings and discuss to what extent previous conflicting stationary approaches provide compatible results. A proper account of causality is found essential in order to obtain the correct result.
authors.affiliation: Laboratoire Kastler Brossel, UPMC-Sorbonne Universités, CNRS, ENS-PSL Research University, Collège de France, 4, place Jussieu, F-75252 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Donaire
authors.affiliation: Laboratoire Kastler Brossel, UPMC-Sorbonne Universités, CNRS, ENS-PSL Research University, Collège de France, 4, place Jussieu, F-75252 Paris, France.
authors.forename: R
authors.initials: R
authors.lastname: Guérout
authors.affiliation: Laboratoire Kastler Brossel, UPMC-Sorbonne Universités, CNRS, ENS-PSL Research University, Collège de France, 4, place Jussieu, F-75252 Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Lambrecht