Fermions with tunable interactions... In the lithium lab we produce ultracold Fermi gases of 6Li to explore out-of-equilibrium dynamics and transport phenomena in strongly correlated fermionic matter. Atoms are confined into light-imprinted potential structures, simulating the motion of electrons in solid state devices. Our main goal is the study of two-dimensional strongly correlated phases, such as superfluidity across the BCS-BEC crossover and its robustness to disorder.

Persistent Currents in Fermionic Rings

Persistent currents in a ring are one of the most striking manifestations of quantum system coherence. The periodic boundary constrains the wavefunction phase to wind in an integer number of complete loops, which gives rise to a current. This happens in materials with a macroscopic coherence, like superconductors or neutral superfluids, but also in mesoscopic metallic rings. Besides being a proxy of quantum phase coherence, persistent currents represent a cornerstone for many applications, from precision sensing to quantum computing, that require a fast and controlled current injection and a reliable readout of its magnitude. In our work, we realize a fast and on-demand generation of persistent currents in atomic Fermi superfluid rings and investigate their connection with vortex nucleation.
We excite persistent current states of on-demand winding number by dynamically imprinting the phase winding in the ring with a tailored laser beam. Using an interferometric probe, we directly accesses the ring phase profile and we consequently readout the current state. We apply our method to an atomic Fermi gas in different interaction regimes, ranging from a bosonic to a fermionic superfluid. Persistent currents in these rotating neutral superfluids are metastable states, interrupted only by a phase slippage that tears out the phase winding. We finally induce the current decay by inserting a small defect in the ring. For currents higher than a critical value, the obstacle triggers the emission of vortices, which reduce the phase winding.
Our work demonstrates fast and accurate control of persistent currents in strongly interacting fermionic superfluids, opening the route for their application in quantum technologies.

G. Del Pace et al.
Imprinting Persistent Currents in Tunable Fermionic Rings
Phys. Rev. X 12, 041037 (2022)

Li people

Nicola Grani
PhD Student
Diego Hernández Rajkov
PhD Student
Giulia Del Pace
Research Fellow
Massimo Inguscio
Scientific Staff
Giacomo Roati
Scientific Staff
Former members:
Klejdja Xhani
Woo Jin Kwon
Francesco Scazza
Andrea Amico
Alessia Burchianti
Chiara Fort
Riccardo Panza
Jorge Seman
Pedro Tavares
Giacomo Valtolina
Matteo Zaccanti

Li contacts

For further information, request of material, job opportunities, please contact:

Giacomo Roati

Li funding

EU Quantum Flagship
Qombs (2018-2021)
PRIN 2017 CEnTraL
Progetto Ente Cassa QuSiM2D
H2020-MSCA-IF-2018 VorDIST
H2020-MSCA-IF-2015 SCOUTFermi2D