We separate Maxwell's equations for background media that allow for both
electric and magnetic time-dependence in a generalized Lorenz gauge. In a
process analogous to the dynamical Casimir effect (DCE) we discuss how surface
plasmon polaritons (SPP)s can be created out of vacuum, via the time-dependent
variation of a dielectric and magnetic insulator at a metal interface for TM
and TE branches, respectively. We suggest how to extend currently proposed DCE
experiments to set up and detect these excitations. Numerical simulations
(without any approximation) indicate that vacuum excited SPPs can be of a
similar magnitude to the photon creation rate in such experiments. Potential
benefits of detecting vacuum excited SPPs, as opposed to DCE photons, are that
parametric enhancement does not require a sealed cavity in the axial direction
and the detection apparatus might be able to use simple phase matching
techniques. For the case of constant permeability, μ, TM branch SPPs and
photons do not suffer from detuning and attenuation like TE photons.Comment: 5 pages, 3 figures, RevTeX; version 2, reference added, minor changes
made; version 3, sections updated, new plots & supplemental notes added (3
pages); version 4, concurs with version published in Physical Review
