The limitations for the coherent manipulation of neutral atoms with
fabricated solid state devices, so-called `atom chips', are addressed.
Specifically, we examine the dominant decoherence mechanism, which is due to
the magnetic noise originating from the surface of the atom chip. It is shown
that the contribution of fluctuations in the chip wires at the shot noise level
is not negligible. We estimate the coherence times and discuss ways to increase
them. Our main conclusion is that future advances should allow for coherence
times as long as one second, a few micrometers away from the surface.Comment: selected papers of the DPG spring meeting `Quantum Optics'
(Osnabrueck, Germany, 4-8 march 2002), submitted to Applied Physics