Cold Atoms Close to Warm Surfaces

We propose to combine matter wave optics and laser cooled and trapped atoms to study the interaction of cold atoms (T<1mK) with warm surfaces (T >> 1K). This will enable us to study then atom-surface interactions in detail. Using an atom where the atomic physics can be calculated from first principles, like Li, will allow us to develop techniques to study the surface and possibly the underlying bulk material. In addition we will have the possibility to modify the atom-surface interaction for transparent dielectrics (like quartz) by applying an additional light potential which will allow to select and change the specific distance where the experiments are most sensitive. We will address the following questions: We propose to conduct detailed experiments on the atom-surface interaction of macroscopic objects including Casimir Polder and QED effects. Emphasis will be given to compare it with the recent predictions from first principle calculations of Li. These experiments will be the basis for using the atom-surface interactions as a probe for surfaces. We will study the interactions of mesoscopic objects with cold atoms and determine the extent to which the atom- surface interaction is modified for atoms interacting with an object which is, at least in one dimension, smaller than the wavelength corresponding to the dominant atomic transition, and possibly smaller than the de Broglie wavelength of the atom itself. We plan to investigate Quantum Reflection of cold atoms from the attractive atom-surface potential. Using the measured atom-surface will allow us to make a detailed comparison with theory. We will study the rate of heat transfer between a surface and a cold atom. One of the most interesting questions, which also effects all the previously discussed measurements, is concerned with the enormous temperature difference between the cold atom and the nearby surface: How long, and how close can one keep a cold atom near a hot surface before significant heating of the atom occurs? How strong does an cold atom couple to the heat bath of the "hot" surface? How long before the quantum mechanical coherence of its external motion is destroyed? In our proposed research we also will address the temperature dependence of the observed effects with an emphasis on the heating and the decoherence in the center of mass motion of the cold atoms close to the surface. In parallel there are many open theoretical questions touched, which will be addressed together in our collaborations, with J. Babb and R. Cote at ITAMP at the Harvard Smithsonian Institute for Astrophysics and P. Milonni at Los Alamos National Laboratory as well as with B. Hessmo and at the University of Uppsala One very interesting and promising development in atom optics are mesoscopic traps and guides for cold atoms nanofabricated on a surface. For these it is essential to know the atom-surface interaction in detail, especially know whether heat transfer and decoherence in the atomic motion occurs.