Dilution and resonance enhanced repulsion in non-equilibrium fluctuation forces

Abstract

In equilibrium, forces induced by fluctuations of the electromagnetic field between electrically polarizable objects (microscopic or macroscopic) in vacuum are always attractive. The force may, however, become repulsive for microscopic particles coupled to thermal baths with different temperatures. We demonstrate that this non-equilibrium repulsion can be realized also between macroscopic objects, as planar slabs, if they are kept at different temperatures. It is shown that repulsion can be enhanced by (i) tuning of material resonances in the thermal region, and by (ii) reducing the dielectric contrast due to "dilution". This can lead to stable equilibrium positions. We discuss the realization of these effects for aerogels, yielding repulsion down to sub-micron distances at realistic porosities.

5 pages, 4 figures

References in corpus (5)

• Non-equilibrium electromagnetic fluctuations: Heat transfer and interactions
• Casimir-Lifshitz force out of thermal equilibrium
• Casimir-Lifshitz force out of thermal equilibrium and heat transfer between arbitrary bodies
• Non-equilibrium Casimir forces: Spheres and sphere-plate
• Reduction of the Casimir force using aerogels

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