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 nano-particles if there is sufficient anisotropy, between a perfectly conducting sphere and a Drude sphere,and between a sufficiently anisotropic electrically polarizable nano-particle and a transverse magnetic conducting plate.

15 pages, 13 figures, to be published in JPCM special issue on Casimir forces; revision includes small clarifications and additional references

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Cited by in corpus (8)

• Axial Casimir Force
• Negative Entropies in Casimir and Casimir-Polder Interactions
• The role of diffraction in the Casimir effect beyond the proximity force approximation
• Casimir Self-Entropy of a Spherical Electromagnetic $\delta$-Function Shell
• Disentangling geometric and dissipative origins of negative Casimir entropies
• Casimir Self-Entropy of an Electromagnetic Thin Sheet
• Casimir Self-Entropy of Nanoparticles with Classical Polarizabilities: Electromagnetic Field Fluctuations
• Negativity of the Casimir self-entropy in spherical geometries