Dilution and resonance enhanced repulsion in non-equilibrium fluctuation forces

Giuseppe Bimonte 1, Thorsten Emig 2, Matthias Kruger 3, Mehran Kardar 3

Physical Review A 84 (2011) 042503

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.

  • 1. Dipartimento di Scienze Fisiche,
    Universita di Napoli Federico II
  • 2. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS),
    CNRS : UMR8626 – Université Paris XI - Paris Sud
  • 3. Department of Physics,
    Massachusetts Institute of Technology