Supplemental online material for:

Universal Aspects of Vortex Reconnections across the BCS-BEC Crossover

 Marek Tylutki1 and Gabriel Wlazłowski1,2

1Faculty of Physics, Warsaw University of Technology
 2Department of Physics, University of Washington

When you use data from this webpage, please make credit to: M. Tylutki, G. Wlazłowski, Phys. Rev. A 103, L051302 (2021)

Vortex reconnections in superfluid system

Vortex reconnection process is a fundamental process in superfluids (systems with vanishing viscosity) allow them for the energy transfer between different length scales and its subsequent dissipation. During the reconnection, vortices approach each other and exchange lines which induce altering of flow pattern. The exchange is accompanied by generation Kelvin waves and emissions of phonons (sound waves).

In out articel we showed that the reconnection dynamics exhibits universal  behaviour across the entire BEC-BCS crossover. The universal scaling is also present for spin-imbalanced systems, where unpaired fermions induce complex structure of the colliding vortices.

See our article: arXiv:2010.15631

Accompanying movies - highlights

Vortex reconnection in unitary Fermi gas with spin-polarization effects 
(UFG-P02)

Collision of two initially perpendicular vortex lines in strongly interacting Fermi gas. In this exotic case one of lines drag inside spin polarization Orange contour plot shows vortex core, while purple dust around the core visualizes local spin-polarization of the gas. Before the reconnection the vortices locally equilibrate via spin diffusion process, and only then the exchange of lines is executed.

Download

Vortex reconnection followed by generation of Kelvin waves 
(UFG-P0-2.5)

Simulation showing vortex reconnection in the unitary Fermi gas. After the reconnections Kelvin waves are induces. This mechanism leads to the energy dissipation in superfluids.  The scaling of the distance between the reconnection points of the two lines as a function of time in form δ(t) ∼ |t−t*|1/2 and can be regarded as universal aspect of the reconnection event.

Download

Towards of concentration of curvature of reconnecting segments. 
(UFG-P0-1.7-line)

Dynamics of the extracted vortex line in the unitary Fermi gas, where the colour code along the line corresponds to a local curvature. It is seen that at the reconnection moment the curvature is concentrated around the point where exchange of line will be executed. 

Download

Movies for data sets

 BCS-P0

Vortex reconnection is weakly interacting Fermi gas (BCS regime).

Download

 UFG-P0-1.7

Vortex reconnection is strongly interacting Fermi gas (unitary regime).

Download

 UFG-P0-2.5

The same as movie UFG-P0-1.7 but with higher lattice resolution.

Download

 BEC-64

Vortex reconnection by means of ETF model (BEC regime)

Download

 BEC-256

Vortex reconnection by means of GPE model on high resolution lattice 2563 (BEC regime)

Download

 BCS-P1

Vortex reconnection is weakly interacting and spin imbalanced Fermi gas (BCS regime). Movie shows location of core (orange surface) and distribution of spin-polarization.

Download

 UFG-P1

Vortex reconnection is strongly interacting and spin imbalanced Fermi gas (unitary regime). Movie shows location of the core (orange surface) and distribution of spin-polarization.

Download

 UFG-P2

The same as movie UFG-P1 but with increased spin imabalnce.

Download

Related materials

Our talks & posters based on materials obtained within this work
  1. Gabriel Wlazłowski, Fermionic superfuidity: from dynamics of a single vortex to quantum turbulence, Optics Group Seminars, University of São Paulo, 27-10-2020, Brazil.
  2. Marek Tylutki, et. al., Vortex Dynamics in the Superfluid Fermi Gas – from Ultracold Gases to Neutron Stars, Extraordinary congress of Polish Physical Society, Warsaw, October 16-18 2020.

Acknowledgments

Faculty of Physics @ WUT

Made with Pingendo Free  Pingendo logo