Observation of Shapiro steps in an ultracold atomic Josephson junction.
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| Title: | Observation of Shapiro steps in an ultracold atomic Josephson junction. |
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| Authors: | Bernhart, Erik (AUTHOR), Röhrle, Marvin (AUTHOR), Singh, Vijay Pal (AUTHOR), Mathey, Ludwig (AUTHOR), Amico, Luigi (AUTHOR), Ott, Herwig (AUTHOR) |
| Source: | Science. 12/11/2025, Vol. 390 Issue 6778, p1130-1133. 4p. |
| Subjects: | Josephson effect, Josephson junctions, Energy dissipation, Phonons, Bose-Einstein condensation, Current-voltage characteristics, Computer simulation, Solitons |
| 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. Editor's summary: In the Josephson effect, a current can flow through an insulating barrier between two superconductors without dissipation. For a high enough current, dissipation does occur, and if microwave radiation is also applied, a series of plateaus—the so-called Shapiro steps—appear in the current-voltage characteristic. Instead of using superconductors, Del Pace et al. and Bernhart et al. observed Shapiro steps in an atomic Josephson junction. The researchers moved a barrier through an ultracold gas at a speed that had a periodically modulated component to emulate microwave radiation. The height of the resulting Shapiro steps in the chemical potential difference was proportional to the frequency of the modulation. —Jelena Stajic [ABSTRACT FROM AUTHOR] |
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| Database: | Psychology and Behavioral Sciences Collection |
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| 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. Editor's summary: In the Josephson effect, a current can flow through an insulating barrier between two superconductors without dissipation. For a high enough current, dissipation does occur, and if microwave radiation is also applied, a series of plateaus—the so-called Shapiro steps—appear in the current-voltage characteristic. Instead of using superconductors, Del Pace et al. and Bernhart et al. observed Shapiro steps in an atomic Josephson junction. The researchers moved a barrier through an ultracold gas at a speed that had a periodically modulated component to emulate microwave radiation. The height of the resulting Shapiro steps in the chemical potential difference was proportional to the frequency of the modulation. —Jelena Stajic [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00368075 |
| DOI: | 10.1126/science.ads9061 |
