Eur. Phys. J. D 15, 113-126 (2001)
https://doi.org/10.1007/s100530170189

Quantum theory of van der Waals interactions between excited atoms and birefringent dielectric surfaces

Laboratoire de Physique des Lasers (UMR 7538 du CNRS.) , Institut Galilée, Université Paris-Nord, 99 avenue J.-B. Clément, 93430 Villetaneuse, France

Corresponding author: ^a ducloy@galilee.univ-paris13.fr

Received: 24 January 2001
Published online: 15 July 2001

Abstract

A theory of van der Waals (vdW) interaction between an atom (in ground or excited state) and a birefringent dielectric surface with an arbitrary orientation of the principal optic axis (C-axis) is presented. Our theoretical approach is based on quantum-mechanical linear response theory, using generalized susceptibilities for both atom and electromagnetic field. Resonant atom-surface coupling is predicted for excited-state atoms interacting with a dispersive dielectric surface, when an atom de-excitation channel gets into resonance with a surface polariton mode. In the non-retarded regime, this resonant coupling can lead to enhanced attractive or repulsive vdW surface forces, as well as to a dissipative coupling increasing the excited-state relaxation. We show that the strongly non-scalar character of the interaction with the birefringent surface produces a C-axis-dependent symmetry-breaking of the atomic wavefunction. Changes of the C-axis orientation may also lead to a frequency shift of the surface polariton mode, allowing for tuning on or off the resonant coupling, resulting in a special type of engineering of surface forces. This is analysed here in the case of cesium level interacting with a sapphire interface, where it is shown that an adequate choice of the sapphire C-axis orientation allows one to transform vdW surface attraction into repulsion, and to interpret recent experimental observations based on selective reflection methods [ H. Failache et al., Phys. Rev. Lett. 83, 5467 (1999)] .