The two-dimensional Bose Gas in box potentials

Overview & Synopsis

Degenerate atomic gases are a versatile tool to study many-body physics. They offer the possibility to explore low-dimension physics, which strongly differs from the three dimensional (3D) case due to the enhanced role of fluctuations. In this work, we study degenerate 2D Bose gases whose original in-plane confinement is uniform and of arbitrary shape. These 2D uniform traps, which we first developed on an existing set-up, were subsequently implemented on a newset-up using versatile optical potentials. We present a series of experiments that take advantage of this flexible geometry. First, we study the static and dynamic behaviours of a uniform gas at the transition between a 3D normal and a 2D superfluid state. We observe the establishement of extended phase coherence, followed, as the gas is quench cooled, by the apparition of topological defects whose scaling is compared to the Kibble-Zurek prediction. Second, we present the first results of the new set-up : we investigate collective effects in light-matter interactions, where the resonance properties of a dense ensemble of atoms are strongly modified with respect to the single atom ones. Last, we develop two experimental proposals for the new set-up. The first one studies how a 2D gas can be uniformly evaporated using the tilted lattice providing the 2D confinement. In the second one, we propose to produce su-percurrents in a deterministic way in ring-shaped traps either by condensing inan artificial gauge field or by implementing a topological vortex pump.