Shapiro steps in strongly-interacting Fermi gases
- Giulia Del Pace
- Diego Hernández-Rajkov
- Vijay Pal Singh
- Nicola Grani
- Marcia Frómeta Fernández
- Giulio Nesti
- Jorge Amin Seman
- Massimo Inguscio
- Luigi Amico
- Giacomo Roati
2025-12-11
Driven many-body systems exhibit diverse and complex dynamical behaviors. Here, we report the observation of Shapiro steps in periodically driven Josephson junctions between strongly interacting Fermi superfluids of ultracold atoms. The height and the width of the observed quantized plateaus in the current-potential characteristics mirror the external drive frequency and the junction nonlinear response. Direct measurements of the current-phase relationship showcase how Shapiro steps arise from the synchronization between the relative phase of the two reservoirs and the external drive. Such a mechanism is further supported by the detection of periodic phase-slippage processes, in the form of vortex-antivortex pairs. Our results are corroborated by a circuital model and numerical simulations. Our work may open prospects for studying emergent nonequilibrium dynamics in quantum many-body systems under external drives.