Abstract

Integrating and miniaturising atom cooling and trapping geometries can be used for efficient and versatile production of quantum degenerate gases in the vicinity of atom chips. This concept has been successfully used in forming a variety of microtraps based on static and oscillating magnetic and electric fields. For example, coherent beam splitters for matter waves have been devised, enabling studies of coherence and thermalisation in ultracold one-dimensional Bose gases.

Here we present further techniques that can be employed to microscopically engineer the environment of quantum gases. The possibilities include forming non-trivial geometries and topologies, such as rings, cylinders and hollow tori. Beyond modifying the trapping potential, control of magnetic fields allows microscopic local and fast temporal tailoring of the interaction strength within the gas, opening the path to a new set of experiments. For example, inhomogeneous interaction strength results in inhomogeneous critical parameters for thermal and quantum phase transitions as well as in inhomogeneous velocity of sound. We will discuss how such inhomogeneities can potentially be used to study proximity effects and phonon production in a constant velocity gas flow undergoing the transition from subsonic to supersonic speed.