Phase synchronization of oscillatory processes in mesoscopic Josephson junctions

• Applicants: Professor Dr. Fabian Hassler; Dr. Sergey Lotkhov
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 445530728

Duality effects of Bloch and Josephson oscillations constitute fascinating new physics with prospective future applications in metrology. Although their footprint was unveiled as early as in the beginning of the nineties, a clear observation of Bloch oscillations has been a great technical challenge over the last decades. During the first funded project phase, we succeeded in synchronising Bloch oscillations in small Josephson junctions and observing dual Shapiro steps of quantised current, IB = 2e x f_drive, where f_drive is the drive frequency of a few GHz. Furthermore, significant theoretical advances have been made in the description of charge dynamics and elaboration of novel circuits. However, thermal fluctuations and Zener tunnelling effects still represent considerable bottlenecks for the further study of duality effects and need to be circumvented by using non-trivial circuit concepts. In the new joint project, we will focus on phase synchronisation effects in circuits with stable and coherent Bloch oscillations driven by both external and on-chip oscillation sources. The purpose of these investigations, while aiming at future applications in current metrology, is to obtain new insight into the synchronisation mechanisms and to achieve substantial improvements in suppressing the above-mentioned error processes. Our goal is to verify the fundamental current-to-frequency relation and the von-Klitzing resistance quantum, I = 2e x f and V/I = R_k = h/4e^2 at the relative accuracy level of better than 100 ppm over a continuous frequency range of 1 GHz.

• DFG Programme: Research Grants