Negative Entropies in Casimir and Casimir-Polder Interactions

K. A. Milton, Y. Li, P. Kalauni, P. Parashar, R. Guérout, G.-L. Ingold, A. Lambrecht und S. Reynaud

Fortschr. Phys. 65, 1600047 (2017) DOI: 10.1002/prop.201600047

It has been increasingly becoming clear that Casimir and Casimir-Polder entropies may be negative in certain regions of temperature and separation. In fact, the occurrence of negative entropy seems to be a nearly ubiquitous phenomenon. This is most highlighted in the quantum vacuum interaction of a nanoparticle with a conducting plate or between two nanoparticles. It has been argued that this phenomenon does not violate physical intuition, since the total entropy, including the self-entropies of the plate and the nanoparticle, should be positive. New calculations, in fact, seem to bear this out at least in certain cases.