Atomic quantum systems still present an important paradigm for the investigation of quantum physics.
Studies range from fundamental issues such as decoherence to application such as quantum sensors
based on the wave-mechanical properties of atoms.
A new direction in this field is based on atom optics, atom interferometry, and neutral-atom quantum information processing using optical micro- and nano-structures. We experimentally investigate the coherence properties of wave packets of the external motion of atoms in periodic optical micro-potentials (optical lattices). Using optical micro-systems, we demonstrate interferometer-type guiding structures for neutral atoms. Combining multiple realizations of these structures, we realize X-shaped beam splitters and more complex systems like the geometries for Mach-Zehnder and Michelson-type interferometers for atoms.
We also experimentally investigate the applicability of micro-optical elements to create multiple far-detuned dipole traps for storing and manipulating qubits inscribed into atoms. Due to the large lateral separation of neighboring potential wells, each trap is individually addressable. The internal states can be prepared, manipulated, and retrieved for the atoms in the individual potential wells. Various schemes for quantum entanglement and two- or multiple-qubit gates will become possible.