We consider the electric- and magnetic-field fluctuations in the vacuum state in the region external to a half space filled with a homogeneous nondissipative dielectric. We discuss an appropriate limit to an ideal metal and concentrate our interest on the renormalized field fluctuations, or equivalently on the renormalized electric and magnetic energy densities, in the proximity of the dielectric-vacuum interface. We show that surface divergences of field fluctuations arise at the interface in an appropriate ideal conductor limit, and that our limiting procedure allows us to discuss their structure in detail. Field fluctuations close to the surface can be investigated through the retarded Casimir-Polder interaction with an appropriate polarizable body.

• Received 29 April 2012

DOI:https://doi.org/10.1103/PhysRevA.86.012122