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The production and manipulation of coherent atomic ensembles has enabled much of the most recent progress in cold-atom physics and quantum optics. Atomic matter waves will serve as an excellent system for exciting future developments in basic research and application - the controlled engineering of quantum states is possible.
We have investigated atom optics with Bose-Einstein condensates and recently studied the phase coherence properties of elongated BECs in detail. We observed that the phase of a BEC is not necessarily uniform but undergoes statistical fluctuations. In particular, we observe BECs where the phase coherence length is smaller than the condensate size, i.e. so called quasi-condensates. I will report on our recent interferometric measurement of the coherence length in the regime where strong phase fluctuations are present in our condensates. The method, which is closely related to the stellar interferometer of Hanbury-Brown and Twiss will be discussed and compared to complementary ways of measuring the coherence length. Using miniaturised trapping and guiding potential based on micro-fabricated optical elements, we achieved progress towards quantum information processing and integrated atom optics. Micro-fabrication enables us to tailor optical dipole potentials to the exact shape needed for these applications. I will present our results on a two-dimensional quantum storage array and integrated geometries for guided atom interferometers. Coherent matter waves also serve as a basis for the development of novel quantum sensors. Atom interferometry has the potential of achieving a highly increased sensitivity for fundamental measurements and applications. I will discuss potential implemations, focusing on the realisation of next generation tests of general relativity with space-based quantum sensors using atom-interferometrical techniques. |