Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 22: Superconductivity – Poster I
TT 22.3: Poster
Monday, March 9, 2026, 18:00–20:00, P1
RF-Driven Josephson Dynamics in an STM-Defined Pb-NbS2 Junction — •Ajla Karic, Rian Ligthart, Alexander LaFleur, Kevin Hauser, Benjamin Froelich, and Fabian D. Natterer — Department of Physics, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland
We use a scanning tunneling microscope to form an ultrasmall Josephson junction between a Pb tip and an NbS2 sample at 1.5 K and investigate how its electromagnetic environment shapes the Josephson response. We apply radio-frequency (RF) driving up to 40 GHz and track the evolution of dI/dV spectra as a function of RF amplitude. The measurements reveal pronounced photon-assisted tunneling features and a strong modulation, suppression, and reemergence of the zero-bias Josephson peak, consistent with a phase-diffusive regime dominated by environmental fluctuations. In ongoing work, we increase the effective junction capacitance to directly probe how controlled changes in the junction capacitance modify the Josephson dynamics. Understanding these environmental effects is essential for identifying the conditions under which STM-based Josephson junctions can be pushed toward more coherent operation relevant for qubit applications.
Keywords: Scanning tunneling microscopy (STM); Josephson junction; Photon-assisted tunneling (PAT); Radio-frequency (RF) driving