74 research outputs found
Mode structure and polaritonic contributions to the Casimir effect in a magneto-dielectric cavity
We present a full analysis of the mode spectrum in a cavity formed by two
parallel plates, one of which is a magneto-dielectric, e.g. a metamaterial,
while the other one is metallic, and obtain dispersion relations in closed
form. The optical properties of the cavity walls are described in terms of
realistic models for the effective permittivity and the permeability. Surface
polaritons, i.e. electromagnetic modes that have at least partly an evanescent
character, are shown to dominate the Casimir interaction at small separations.
We analyze in detail the s-polarized polaritons, which are a characteristic
feature of a magneto-dielectric configuration, and discuss their role in the
repulsive Casimir force.Comment: 14 pages, 8 figure
Modal Approach to Casimir Forces in Periodic Structures
We present a modal approach to calculate finite temperature Casimir
interactions between two periodically modulated surfaces. The scattering
formula is used and the reflection matrices of the patterned surfaces are
calculated decomposing the electromagnetic field into the natural modes of the
structures. The Casimir force gradient from a deeply etched silicon grating is
evaluated using the modal approach and compared to experiment for validation.
The Casimir force from a two dimensional periodic structure is computed and
deviations from the proximity force approximation examined.Comment: 13 pages, 7 figure
Optical BCS conductivity at imaginary frequencies and dispersion energies of superconductors
We present an efficient expression for the analytic continuation to arbitrary
complex frequencies of the complex optical and AC conductivity of a homogeneous
superconductor with arbitrary mean free path. Knowledge of this quantity is
fundamental in the calculation of thermodynamic potentials and dispersion
energies involving type-I superconducting bodies. When considered for imaginary
frequencies, our formula evaluates faster than previous schemes involving
Kramers--Kronig transforms. A number of applications illustrates its
efficiency: a simplified low-frequency expansion of the conductivity, the
electromagnetic bulk self-energy due to longitudinal plasma oscillations, and
the Casimir free energy of a superconducting cavity.Comment: 20 pages, 7 figures, calculation of Casimir energy adde
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