Environment-induced decoherence in miniaturized atom traps

Summary form only given. Magnetic and optical traps above microstructured surfaces provide a strong confinement for neutral atomic matter waves. Applications range from integrated atom optics to quantum computing. Decoherence is a major issue in this environment, particularly when one considers the dramatic temperature difference between the ultracold gas and the surface. We consider simple trap geometries and compute the noise spectrum of thermally excited electromagnetic fields. If the trap is located in the near field of the substrate, the field fluctuations are largely increased compared to the level of the blackbody field. This leads to much shorter coherence and lifetimes of the trapped atoms. The corresponding time constants are computed for magnetic and optical traps. Analytical estimates for the size dependence of the noise spectrum are given. We finally discuss prospects for the coherent transport of matter waves.