  We study the electromagnetic coupling and concomitant heating of a particle
in a miniaturized trap close to a solid surface. Two dominant heating
mechanisms are identified: proximity fields generated by thermally excited
currents in the absorbing solid and time-dependent image potentials due to
elastic surface distortions (Rayleigh phonons). Estimates for the lifetime of
the trap ground state are given. Ions are particularly sensitive to electric
proximity fields: for a silver substrate, we find a lifetime below one second
at distances closer than some ten micrometer to the surface. Neutral atoms may
approach the surface more closely: if they have a magnetic moment, a minimum
distance of one micrometer is estimated in tight traps, the heat being
transferred via magnetic proximity fields. For spinless atoms, heat is
transferred by inelastic scattering of virtual photons off surface phonons. The
corresponding lifetime, however, is estimated to be extremely long compared to
the timescale of typical experiments.
