# Coherent and dissipative transport in a Josephson junction between fermionic superfluids of $^6$Li atoms

## TL;DR

This paper reports experimental observations of quantum transport in ultracold fermionic superfluids, revealing coherent Josephson dynamics, phase-slippage, vortex proliferation, and dissipation effects in a fermionic Josephson junction.

## Contribution

It presents the first experimental realization of a Josephson junction with ultracold fermionic superfluids and explores both coherent and dissipative transport regimes.

## Key findings

- Observation of coherent Josephson oscillations
- Identification of phase-slippage events via vortices
- Discovery of a strongly dissipative regime affecting junction operation

## Abstract

Quantum systems out of equilibrium offer the possibility of understanding intriguing and challenging problems in modern physics. Studying transport properties is not only valuable to unveil fundamental properties of quantum matter but it is also an excellent tool for developing new quantum devices which inherently employ quantum-mechanical effects. In this contribution, we present our experimental studies on quantum transport using ultracold Fermi gases of $^6$Li atoms. We realize the analogous of a Josephson junction by bisecting fermionic superfluids by a thin optical barrier. We observe coherent dynamics in both the population and in the relative phase between the two reservoirs. For critical parameters, the superfluid dynamics exhibits both coherent and resistive flow due to phase-slippage events manifesting as vortices propagating into the bulk. We uncover also a regime of strong dissipation where the junction operation is irreversibly affected by vortex proliferation. Our studies open new directions for investigating dissipation and superfluid transport in strongly correlated fermionic systems.