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TT: Fachverband Tiefe Temperaturen
TT 33: Focus Session: Nanomechanical Systems for Classical and Quantum Sensing I (joint session TT/DY/HL/QI)
TT 33.4: Vortrag
Dienstag, 19. März 2024, 12:30–12:45, H 3007
Signatures of Josephson force in a vibrating carbon nanotube junction — •Andreas K. Hüttel1,2, Jukka-Pekka Kaikkonen2, Keijo Korhonen2, and Pertti Hakonen2 — 1Institute for Experimental and Applied Physics, Universität Regensburg, Regensburg, Germany — 2Low Temperature Laboratory, Dept. of Applied Physics, Aalto University, Espoo, Finland
A carbon nanotube suspended between superconducting electrodes acts simultaneously as nanomechanical resonator and as a Josephson junction. Its energy-dependent density of states and with that displacement-dependent critical current further adds to the complexity of the system, as does both mechanical and electronic nonlinearity. Measurements on such a system display complex behaviour of the vibrational resonance with respect to junction biasing. Strikingly, the resonance frequency appears to decrease in a distinct parameter region where the biasing is similar in size to the junction switching current.
Using highly parallelized Julia code, we numerically solve the coupled differential equation system of the driven (via an ac gate voltage and ac current or voltage bias) system for realistic device parameters and characterize the evolving steady state. Specific attention is given to the impact of the Josephson junction behaviour on the mechanical resonance frequency and the vibration amplitude, and on the ac signal simultaneously acting on gate and bias.
Keywords: carbon nanotube; Josephson junction; NEMS; beam resonator; Julia