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TT: Fachverband Tiefe Temperaturen
TT 73: Superconductivity: Tunneling and Josephson Junctions
TT 73.3: Vortrag
Donnerstag, 12. März 2026, 10:00–10:15, CHE/0089
Voltage fluctuations in atomic-scale Josephson junctions — •Verena Caspari1, Werner M. J. van Weerdenburg1, Christian Lotze1, Clemens B. Winkelmann2, and Katharina J. Franke1 — 1Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany — 2Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG-Pheliqs, Grenoble, France
Phase diffusion in Josephson junctions and the switching from the superconducting to the quasiparticle branch can be explained by the dynamics of a fictitious phase particle in the tilted washboard potential. Usually, only the average voltage is measured[1].
Here, we measure the voltage fluctuations in single-atom Pb-Pb junctions with MHz-bandwidth using a scanning tunneling microscope. In the current-bias regime, the current-voltage V(I) curves show a hysteretic behavior that allows to set the junction into the phase-diffusion regime, where we observe multi-level transitions in time traces. These can be interpreted as phase-slips events leading to the finite average voltage in the superconducting state. In the voltage-bias regime, we observe bistabilities indicating the transition between the superconducting and the quasiparticle branch. Our experiments allow access to the phase-slip dynamics in the STM-based Josephson junction.
[1] R. L. Kautz, J. M. Martinis, Phys. Rev. B 42, 9903 (1990)
Keywords: Josephson junction; phase dynamics; STM