Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 7: Ultracold Matter II – Bosons (joint session Q/A)

Q 7.6: Vortrag

Montag, 2. März 2026, 18:15–18:30, P 2

Vortex nucleation studied through spatially-resolved velocity fields — •Elinor Kath, Jelte Duchene, Hanyi Jang, Helmut Strobel, and Markus K. Oberthaler — Kirchhoff-Institut für Physik, Universität Heidelberg

We developed a method to measure spatially resolved superfluid velocity fields from a single experimental realisation. This technique grants direct access to dynamical properties that remain hidden in density images, like phase gradients, transport mechanisms, and turbulent flow patterns.

The nucleation of vortices is associated with a rise in incompressible kinetic energy, drawn from the kinetic energy's compressible, phononic part. By extracting velocity fields we obtain the full kinetic energy and separate its compressible (phononic) and incompressible (vortical) components. This allows us to study the conversion of compressible to incompressible energy during vortex nucleation.

We create a vortex gas by strongly distorting the condensate's phase and density. We track the appearance of vortices in time through density depletions, the curl of the velocity field, and the evolving energy balance, making a first step towards the study of how quantized vortices first form in quantum fluids, how turbulence initiates, how different excitations redistribute energy.

Keywords: Velocity Field; Turbulence; Vortex; Vortices