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Ultima descărcare din IBN: 2023-07-15 14:37 |
SM ISO690:2012 KRASNOV, Vladimir. Observation of a gradual collective excitation of a geometrical resonance in an array of Nb/NbSi/Nb Josephson junctions with increasing number of synchronized junctions. In: The 12th international conference on intrinsic Josephson effect and horizons of superconducting spintronics, 22-25 octombrie 2021, Chişinău. Chişinău: 2021, p. 48. ISBN 978-9975-47-215-9. |
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The 12th international conference on intrinsic Josephson effect and horizons of superconducting spintronics 2021 | |||||
Conferința "The 12th international conference on intrinsic Josephson effect and horizons of superconducting spintronics" Chişinău, Moldova, 22-25 octombrie 2021 | |||||
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Pag. 48-48 | |||||
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Synchronization of many Josephson junctions (JJs) is required for achieving significant emission power from Josephson oscillators [1]. One of the most promising strategies of synchronization is via collective excitation of a geometrical resonance either inside [1] or outside [2] the junction. Successful synchronization of up to 9000 JJ’s coupled to an external cavity mode, accompanied by a coherent superradiant emission, has been demonstrated in a 1D junction array [3]. However, dynamics of such synchronization is not fully understood: it depends strongly on the array geometry [3], a specific mode of the geometrical resonance [2,3] and many other factors [1]. Here we study experimentally a 1D array of Nb/NbSi/Nb JJ’s, consisting of 7 meander lines with 1000 JJs in each line, similar to those studied in Refs. [2,3]. The JJs exhibit a hysteresis in current- voltage (I-V) characteristics, presumably of thermal origin. Presence of a small inhomogeneity (specifically introduced by applying a small magnetic field) together with the hysteresis, allows one-by-one switching of JJs from the superconducting to the resistive state. We observe that above a certain number of JJs, N≳100, a resonant step starts to develop in the I-V. As shown in Ref. [3] the step is caused by a collective excitation of a cavity mode in the array electrode. The step amplitude gradually increases with increasing N, which is accompanied by a parabolic-like enhancement of the emission power, measured with an external bolometer. Our observation provides a clear evidence for the mutual feedback between the cavity mode and the oscillating JJs. Such the feedback provides an effective mechanism for array synchronization and coherent emission. |
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