Research database

Understanding the behavior of inhomogenous superfluids is fundamental for comprehending diverse physical systems, ranging from superconductors to neutron stars. This project aims to explore inhomogeneous superfluid dynamics, focusing on how pair-breaking, thermal excitations, or spin imbalance, influence superfluid behavior. They lead to a spatially varying order parameter, adding complexity to the system. Ultracold atomic gases provide an ideal platform to investigate these phenomena, due to controllable trapping geometries and interactions. By tuning interactions using Feshbach resonances, different superfluidity regimes are obtained: the strongly interacting unitary Fermi gas (UFG), the weakly interacting Bardeen-Cooper-Schrieffer (BCS) superfluid, and the Bose-Einstein condensate (BEC) of tightly bound molecules. To theoretically model these systems, advanced computational techniques, including time-dependent density functional theory (TDASLDA) for fermionic superfluids and the Zaremba-Nikuni-Griffin (ZNG) model for finite-temperature BECs will be imployed. This project focuses on open questions on fermionic superfluid dynamics. Benchmark studies will be also performed on the BEC limit at finite temperature, searching so for universal properties from bosonic to fermionic superfluids. This project has two primary objectives: 1) Investigation of the dynamics of coupled fermionic superfluid rings, concentrating on the Kelvin-Helmholtz instability (KHI) and Josephson effects. The effect of complex vortex core structure, mutual friction and pair-breaking on the KHI growth rate will be investigated, from UFG to BCS regime, and at both zero and finite temperature. In addition, Josephson effect between two coupled fermionic ring superfluids in the presence of persistent current will be studied. In particular, the main focus will be on the dynamics of Josephson vortices formed at the barrier, and their response to an initial acceleration. 2) The effect of spin imbalance on the stability of persistent currents and vortices dynamics will be investigated searching for new probes of exotic phases such as FFLO states. This project will increase our understanding of inhomogoneous superfluids dynamics and will have implications in future atomtronic devices and quantum simulators.