Van der Waals-Zeeman Colloquium

Tuesday, 3 November 2009, 16:00

Ultracold atoms interacting with solid-state micro- and nanostructures

Dr. Philipp Treutlein
Max-Planck-Institut für Quantenoptik und LMU München, Fakultät für Physik

Ultracold atoms in chip-based microtraps, so-called "atom chips", enable intriguing experiments at the interface of quantum optics and solid-state physics.

On the one hand, microstructures on the chip can be used to coherently manipulate the quantum state of the atoms. I will report experiments in which we use microwave near-fields on miniaturized waveguides to generate trapping potentials which depend on the atomic internal state. We observe coherent dynamics of two-component Bose-Einstein condensates in such a potential and perform trapped-atom interferometry with internal-state labeling. We exploit state-dependent atomic collisions to prepare spin-squeezed states of the condensate and quantify the depth of entanglement in this many-particle system. Possible applications of these techniques are chip-based atomic clocks beyond the standard quantum limit and quantum information processing.

On the other hand, the atoms can serve as a probe for the dynamics of on-chip solid-state systems such as tiny mechanical oscillators. As a first experimental step in this direction we have used a BEC to read out the vibrations of a microcantilever. A particularly exciting perspective of such experiments is to build hybrid quantum systems in which the atoms are used for coherent manipulation, preparation, and measurement of the oscillators' state.