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Q: Fachverband Quantenoptik und Photonik

Q 36: Ultra-cold Atoms, Ions and BEC III (joint session A/Q)

Q 36.3: Vortrag

Mittwoch, 12. März 2025, 11:45–12:00, KlHS Mathe

Shapiro steps in driven atomic Josephson junctions — •Vijay Singh¹, E. Bernhart², M. Röhrle², H. Ott², G. Del Pace³, D. Hernandez-Rajkov³, N. Grani³, M. Frometa Fernandez³, G. Nesti³, J. A. Seman⁴, M. Inguscio³, G. Roati³, L. Mathey⁵, and Luigi Amico¹ — ¹QRC, TII, Abu Dhabi, UAE — ²RPTU Kaiserslautern, Germany — ³LENS, University of Florence, Italy — ⁴UNAM Mexico — ⁵ZOQ and IQP, Universität Hamburg, Germany

We report the observation of Shapiro steps in atomic Josephson junctions formed by coupling two ultracold atom clouds. As predicted in the theoretical proposal, periodic modulation of the position of the tunneling barrier induces Shapiro steps in the dc current-chemical potential characteristic. Experiments on a Josephson junction of ⁸⁷Rb atoms display Shapiro steps in the current-potential characteristic, exhibiting universal features and providing key insight into the microscopic dissipative dynamics associated with phonon emission and soliton nucleation. Experiments with strongly-interacting Fermi superfluids of ultracold atoms also show the creation of Shapiro steps in the current-potential characteristics, with their height and width reflecting the external drive frequency and the junction nonlinear response. Direct measurements of the current-phase relationship reveal the underlying dissipation mechanism via the emission of vortex-antivortex pairs. These results establish a significant connection between superconducting and atomic Josephson dynamics, with unprecedented control and flexibility over physical parameters. Finally, our results lay the foundation for the development of new atomtronic devices and sensors.

Keywords: Atomic Josephson junction; Shapiro steps