Negative Casimir entropies in nanoparticle interactions
Abstract
Negative entropy has been known in Casimir systems for some time. For example, it can occur between parallel metallic plates modeled by a realistic Drude permittivity. Less well known is that negative entropy can occur purely geometrically, say between a perfectly conducting sphere and a conducting plate. The latter effect is most pronounced in the dipole approximation, which is reliable when the size of the sphere is small compared to the separation between the sphere and the plate. Therefore, here we examine cases where negative entropy can occur between two electrically and magnetically polarizable nanoparticles or atoms, which need not be isotropic, and between such a small object and a conducting plate. Negative entropy can occur even between two perfectly conducting spheres, between two electrically polarizable nanoparticles if there is sufficient anisotropy, between a perfectly conducting sphere and a Drude sphere, and between a sufficiently anisotropic electrically polarizable nanoparticle and a transverse magnetic conducting plate.
 Publication:

Journal of Physics Condensed Matter
 Pub Date:
 June 2015
 DOI:
 10.1088/09538984/27/21/214003
 arXiv:
 arXiv:1405.0311
 Bibcode:
 2015JPCM...27u4003M
 Keywords:

 Quantum Physics;
 High Energy Physics  Theory
 EPrint:
 15 pages, 13 figures, to be published in JPCM special issue on Casimir forces