Hannover 2020 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 25: Quantum gases (Bosons) IV
Q 25.1: Vortrag
Mittwoch, 11. März 2020, 11:00–11:15, e214
Exciting an interaction-tuneable uniform Bose gas confined in flatland — •Julian Schmitt, Panagiotis Christodoulou, Maciej Galka, Nishant Dogra, Jay Man, and Zoran Hadzibabic — Cavendish Laboratory, University of Cambridge, UK
Dimensionality plays a crucial role in governing the nature of phase transitions in a system. The marginal case of two dimensions is especially interesting, where an interacting Bose gas exhibits superfluidity via the Berezinski-Kosterlitz-Thouless (BKT) topological phase transition mediated by the binding of vortices.
In this talk, I will present our recent experimental investigations to probe the collective excitations in a two-dimensional uniform Bose gas trapped in an optically sculpted box potential. Our system is derived from a Bose-Einstein-condensate of 39K atoms with tuneable interactions due to a broad Feshbach resonance. Subsequently, the atoms are confined in a two-dimensional homogeneous optical box created using two different digital micromirror devices. By applying temporally changing spatial potentials, we force the superfluid out of equilibrium and monitor its density response. The emergent sound modes in the system are studied as a function of interaction strength and temperature. Importantly, the tuneability of the interactions allows us to explore the behaviour of the elementary excitations near the BKT phase transition under hydrodynamic conditions. Our system provides an ideal platform to study out-of-equilibrium situations with externally controlled dissipation channels, paving the way for studies of turbulent cascades in two-dimensional systems.