# Vortices and antivortices in two-dimensional ultracold Fermi gases

## TL;DR

This paper investigates the behavior of vortices and antivortices in two-dimensional ultracold Fermi gases, highlighting their role in quantum phase transitions and how their properties depend on interaction strength.

## Contribution

It provides a theoretical analysis using renormalization group methods to show the dependence of vortex behavior on interaction strength in 2D superfluid fermions.

## Key findings

- Universal jump of superfluid density depends on interaction strength
- Critical temperature is influenced by vortex unbinding transition
- Results serve as benchmarks for future experiments

## Abstract

Vortices are commonly observed in the context of classical hydrodynamics: from whirlpools after stirring the coffee in a cup to a violent atmospheric phenomenon such as a tornado, all classical vortices are characterized by an arbitrary circulation value of the local velocity field. On the other hand the appearance of vortices with quantized circulation represents one of the fundamental signatures of macroscopic quantum phenomena. In two-dimensional superfluids quantized vortices play a key role in determining finite-temperature properties, as the superfluid phase and the normal state are separated by a vortex unbinding transition, the Berezinskii-Kosterlitz-Thouless transition. Very recent experiments with two-dimensional superfluid fermions motivate the present work: we present theoretical results based on the renormalization group showing that the universal jump of the superfluid density and the critical temperature crucially depend on the interaction strength, providing a strong benchmark for forthcoming investigations.