Nonequilibrium thermal Casimir-Polder forces

We study the nonequilibrium Casimir-Polder force on an atom prepared in an incoherent superposition of internal energy-eigenstates, which is placed in a magnetoelectric environment of nonuniform temperature. After solving the coupled atom--field dynamics within the framework of macroscopic quantum electrodynamics, we derive a general expression for the thermal Casimir-Polder force.Comment: 5 page

Non-Perturbative Theory of Dispersion Interactions

Some open questions exist with fluctuation-induced forces between extended dipoles. Conventional intuition derives from large-separation perturbative approximations to dispersion force theory. Here we present a full non-perturbative theory. In addition we discuss how one can take into account finite dipole size corrections. It is of fundamental value to investigate the limits of validity of the perturbative dispersion force theory.Comment: 9 pages, no figure

Casimir-Polder interaction of fullerene molecules with surfaces

We calculate the thermal Casimir--Polder potential of C60 and C70 fullerene molecules near gold and silicon nitride surfaces, motivated by their relevance for molecular matter wave interference experiments. We obtain the coefficients governing the asymptotic power laws of the interaction in the thermal, retarded and nonretarded distance regimes and evaluate the full potential numerically. The interaction is found to be dominated by electronic transitions, and hence independent of the internal temperature of the molecules. The contributions from phonon transitions, which are affected by the molecular temperature, give rise to only a small correction. Moreover, we find that the sizeable molecular line widths of thermal fullerenes may modify the nonretarded interaction, depending on the model used. Detailed measurements of the nonretarded potential of fullerene thus allow one to distinguish between different theories of incorporating damping.Comment: 9 pages, 8 figures, 9 table

Fine structure of "zero-mode" Landau levels in HgTe/HgCdTe quantum wells

HgTe/HgCdTe quantum wells with the inverted band structure have been probed using far infrared magneto-spectroscopy. Realistic calculations of Landau level diagrams have been performed to identify the observed transitions. Investigations have been greatly focused on the magnetic field dependence of the peculiar pair of "zero-mode" Landau levels which characteristically split from the upper conduction and bottom valence bands, and merge under the applied magnetic field. The observed avoided crossing of these levels is tentatively attributed to the bulk inversion asymmetry of zinc blend compounds.Comment: 5 pages, 4 figure

Quasi-ballistic transport in HgTe quantum-well nanostructures

The transport properties of micrometer scale structures fabricated from high-mobility HgTe quantum-wells have been investigated. A special photoresist and Ti masks were used, which allow for the fabrication of devices with characteristic dimensions down to 0.45 $\mu$m. Evidence that the transport properties are dominated by ballistic effects in these structures is presented. Monte Carlo simulations of semi-classical electron trajectories show good agreement with the experiment.Comment: 3 pages, 3 figures; minor revisions: replaced "inelastic mean free path" with "transport mean free path"; corrected typing errors; restructered most paragraphs for easier reading; accepted for publication in AP

Matter-screened Casimir force and Casimir-Polder force in planar structures

Using a recently developed theory of the Casimir force (Raabe C and Welsch D-G 2005 Phys. Rev. A 71 013814), we calculate the force that acts on a plate in front of a planar wall and the force that acts on the plate in the case where the plate is part of matter that fills the space in front of the wall. We show that in the limit of a dielectric plate whose permittivity is close to unity, the force obtained in the former case reduces to the ordinary, i.e., unscreened Casimir-Polder force acting on isolated atoms. In the latter case, the theory yields the Casimir-Polder force that is screened by the surrounding matter.Comment: 11 pages, 1 figure -- published online at J. Opt. B on Nov 16 200