Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

Q: Fachverband Quantenoptik und Photonik

Q 62: Ultra-cold Atoms, Ions and BEC IV (joint session A/Q)

Q 62.6: Vortrag

Donnerstag, 5. März 2026, 15:45–16:00, N 1

Vortices in a 2D fermionic superfluid — •Hans Leonard Michel, Artak Mkrtchyan, Moritz von Usslar, René Henke, Cesar Cabrera, and Henning Moritz — Institut für Quantenphysik, Universität Hamburg, Hamburg, Germany

Quantised vortices are widely studied excitations in superfluid systems from helium to ultracold Bose Einstein condensates. While many experiments observed vortices in 3D systems, few realisations were made in 2D systems and none in the 2D BEC-BCS crossover. Here, we will report on the deterministic creation and observation of vortices and their phase quantisation in homogeneous 2D ultracold Fermi gases.

We prepare the homogeneous 2D disk shaped systems by freezing out the vertical motion and imposing a circular outer radial barrier. The vortices are detected by ramping to a quasi-3D regime and subsequent time of flight imaging. This method allows us to reliably create and detect single vortex anti-vortex pairs as well as doubly charged vortices across the BEC-BCS crossover. We confirm that these vortices are quantised by observing the phase profile using matter wave interferometry. To this end, we let the central disk shaped region interfere with an annular outer gas as phase reference after ramping to 3D. Our observation of concentric rings and spirals with one or two arms when creating vortices with no, single or double charge confirms the quantisation of the phase of the vortex. Our measurements provide proof of phase coherence and strong evidence for superfluidity in these strongly interacting quantum fluids across the BEC-BCS crossover.

Keywords: Superfluidity; Reduced dimensionality; 2D Fermi gas; Vortices; Strongly correlated