"Tunneling effects in strongly-correlated Fermi superfluids" (Prof. Giacomo Roati)

Datum: 03.11.2026
Uhrzeit: 14:30
Vortragende(r): Prof. Giacomo Roati
CNR-INO and LENS, Sesto Fiorentino, Italy
Ort: Max Planck Institute of Quantum Optics
Raum: Herbert Walther Lecture Hall
Gastgeber: MPQ

"Quantum mechanical tunneling underlies a wide range of fundamental phenomena and enables the operation of diverse electronic devices, from flash memories to SQUID magnetometers [1]. Its simplest realization is the tunnel junction, formed by coupling two conductors through a thin insulating barrier. As a minimal and well-controlled architecture, tunnel junctions provide direct access to the many-body processes governing mesoscopic quantum transport [2], which are ultimately set by the spectrum of elementary excitations above the ground state.

Here, we present tunneling experiments in strongly interacting atomic Fermi gases across the superfluid transition. We demonstrate that supercurrents and normal currents reflect their connection to the superfluid order parameter amplitude, the pair condensate density, and the associated excitation modes [3, 4]. Finally, by periodically modulating the atomic junction with an ac drive, we show the onset of Shapiro steps dynamics, revealing their origin in the synchronization between the relative phase of the two reservoirs and the external drive [5].

[1] S. Datta, Electronic transport in mesoscopic systems (Cambridge University Press, 1997).
[2] D. Pines and P. Nozieres, Theory of quantum liquids, Vol. 1
(Perseus Books Publishing, Cambridge, MA, 1999).
[3] W. J. Kwon, G. Del Pace, R. Panza, M. Inguscio, W. Zwerger, M. Zaccanti, F. Scazza, and G. Roati, Strongly correlated superfluid order parameters from dc Josephson supercurrents, Science 369, 84 (2020).
[4] G. Del Pace, W. J. Kwon, M. Zaccanti, G. Roati, and F. Scazza, Tunneling Transport of Unitary Fermions across the Superfluid Transition, Phys. Rev. Lett. 126, 055301 (2021)
[5] G. Del Pace, D. Hernández-Rajkov, V. P. Singh, N. Grani, M. Frómeta Fernández, G. Nesti, J. A. Seman, M. Inguscio, L. Amico, and G. Roati, Shapiro steps in strongly-interacting Fermi gases, Science 390, 6778 (2025).