Heating of trapped atoms near thermal surfaces

Abstract

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