253 research outputs found
The Casimir force between rough metallic plates
The Casimir force between two metallic plates is affected by their roughness
state. This effect is usually calculated through the so-called `proximity force
approximation' which is only valid for small enough wavevectors in the spectrum
of the roughness profile. We introduce here a more general description with a
wavevector-dependent roughness sensitivity of the Casimir effect. Since the
proximity force approximation underestimates the effect, a measurement of the
roughness spectrum is needed to achieve the desired level of accuracy in the
theory-experiment comparison.Comment: 7 pages, 1 figure, epl style, minor change
Casimir interaction between a sphere and a grating
We derive the explicit expression for the Casimir energy between a sphere and
a 1D grating, in terms of the sphere and grating reflection matrices, and valid
for arbitrary materials, sphere radius, and grating geometric parameters. We
then numerically calculate the Casimir energy between a metallic (gold) sphere
and a dielectric (fused silica) lamellar grating at room temperature, and
explore its dependence on the sphere radius, grating-sphere separation, and
lateral displacement. We quantitatively investigate the geometrical dependence
of the interaction, which is sensitive to the grating height and filling
factor, and show how the sphere can be used as a local sensor of the Casimir
force geometric features. To this purpose we mostly concentrate on separations
and sphere radii of the same order of the grating parameters (here of the order
of one micrometer). We also investigate the lateral component of the Casimir
force, resulting from the absence of translational invariance. We compare our
results with those obtained within the proximity force approximation (PFA).
When applied to the sphere only, PFA overestimates the strength of the
attractive interaction, and we find that the discrepancy is larger in the
sphere-grating than in the sphere-plane geometry. On the other hand, when PFA
is applied to both sphere and grating, it provides a better estimate of the
exact results, simply because the effect of a single grating is underestimated,
thus leading to a partial compensation of errors.Comment: 16 pages, 7 figure
HYPER and gravitational decoherence
We study the decoherence process associated with the scattering of stochastic
backgrounds of gravitational waves. We show that it has a negligible influence
on HYPER-like atomic interferometers although it may dominate decoherence of
macroscopic motions, such as the planetary motion of the Moon around the Earth.Comment: 9 pages, 4 figures, HYPER Symposium 2002
atomoptic.iota.u-psud.fr/hyper
The Casimir effect in the sphere-plane geometry
We present calculations of the Casimir interaction between a sphere and a
plane, using a multipolar expansion of the scattering formula. This
configuration enables us to study the nontrivial dependence of the Casimir
force on the geometry, and its correlations with the effects of imperfect
reflection and temperature. The accuracy of the Proximity Force Approximation
(PFA) is assessed, and is shown to be affected by imperfect reflexion. Our
analytical and numerical results at ambient temperature show a rich variety of
interplays between the effects of curvature, temperature, finite conductivity,
and dissipation.Comment: Proceedings of the 10th International Conference "Quantum Field
Theory Under the Influence of External Conditions" (Benasque, Spain, 2011);
10 pages and 6 figure
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