engleski

Medium-assisted vacuum force

We discuss some implications of a very recently obtained result for the force on a slab in a planar cavity based on the calculation of the vacuum Lorentz force [C. Raabe and D.-G. Welsch, Phys. Rev. A, 71 (2005) 013814]. We demonstrate that, according to this formula, the total force on the slab consists of a medium-screened Casimir force and, in addition to it, a medium-assisted force. In the Lifshitz configuration, the medium-assisted force is proportional to 1/d at small distances and is very small compared with the corresponding van der Waals force. At large distances, however, it is proportional to ~ 1/d^4 and is comparable with the Casimir force, especially for denser media. The exponents in these power laws decrease by 1 in the case of a thin slab. The formula for the medium-assisted force also describes the force on the cavity medium, which has similar properties. For dilute media, it implies an atom-mirror interaction of the Coulomb type at small and of the Casimir-Polder type at large atom-mirror istances. For a perfectly refecting mirror, the latter force is effectively three-times smaller than the Casimir-Polder force.

medium asssted force; vacuum force; Casimir force; planar cavity

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