Observation of Shapiro steps in an ultracold atomic Josephson junction

Abstract

The current-voltage characteristic of a driven superconducting Josephson junction displays discrete steps. This phenomenon, called the Shapiro steps, forms today’s voltage standard. In this work, we report the observation of Shapiro steps in a driven Josephson junction in a gas of ultracold atoms. We demonstrate that the steps exhibit universal features and provide insight into the microscopic dissipative dynamics that we directly observe in the experiment. We find that the steps are directly connected to phonon emission and nucleation of solitonic excitations, whose dynamics we follow in space and time. The experimental results are underpinned by extensive numerical simulations based on classical-field dynamics and may enable metrological and fundamental advances.

Affiliated Institutions

• Universität Hamburg DE
• Max Planck Institute for the Structure and Dynamics of Matter DE
• Istituto Nazionale di Fisica Nucleare, Sezione di Catania IT
• University of Catania IT
• University of Koblenz and Landau DE
• Technology Innovation Institute AE
• Hamburg Centre for Ultrafast Imaging

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