Casimir-Polder effect with thermally excited surfaces

A Laliotis (1) , M Ducloy (1)

1 LPL - Laboratoire de Physique des Lasers

We take a closer look at the fundamental Casimir-Polder interaction between quantum particles and dispersive dielectric surfaces with surface polariton or plasmon resonances. Linear response theory shows that in the near field, van der Waals, regime the free energy shift of a particle contains a thermal component that depends exclusively on the population/excitation of the evanescent surface polariton/plasmon modes. Our work makes evident the link between particle surface interaction and near field thermal emission and demonstrates how this can be used to engineer Casimir-Polder forces. We also examine how the exotic effects of surface waves are washed out as the distance from the surface increases. In the case of molecules or excited state atoms, far field approximations result in a classical dipole-dipole interaction which depends on the surface reflectivity and the mean number of photons at the frequency of the atomic/molecular transition. Finally we present numerical results for the CP interaction between Cs atoms and various dielectric surfaces with a single polariton resonance and discuss the implications of temperature and retardation effects for specific spectroscopic experiments. The Casimir-Polder (CP) interaction between a polar-isable quantum object (atom or molecule) and a surface arises from quantum fluctuations in vacuum. It's an excellent candidate for fundamental tests of cavity quantum electrodynamics and crucial for any experiments attempting to measure non-Newtonian gravity interactions [1, 2]. CP forces are also relevant in physical chemistry playing an important role in the interpretation of physical phenomena such as atomic adsorption and desorption from hot surfaces or even surface chemistry and cataly-sis. The continuous urge for miniaturisation has led to integrated devices, such as atom and molecule chips [3– 6], used for a variety of applications and more recently tapered nano-fibers were used to trap atoms at distances as small as 200 nm away from the surface [7–9], where atom-surface forces become exceedingly relevant. Novel trapping schemes that exploit the complexity of the van der Waals (vdW) potential of excited atoms have also been proposed [10]. The most basic description of the CP effect is that of a classical dipole interacting with its surface induced image. This approach is mostly valid in the vdW (z

Domaines: Physique Quantique [quant-ph]

A Laliotis, M Ducloy. Casimir-Polder effect with thermally excited surfaces. Physical Review Online Archive (PROLA), 2015, pp.9. ⟨10.1103/PhysRevA.91.052506⟩. ⟨hal-01153740⟩