Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 9: SC: Poster Session

TT 9.40: Poster

Montag, 22. März 2010, 14:00–18:00, Poster A

Simulation of the I-V characteristics of short arrays of small Josephson junctions — •Felix Maibaum and Alexander Zorin — Physikalisch-Technische Bundesanstalt Braunschweig

Small single Josephson junctions and short serial arrays of these elements whith comparable charging- and Josephson energies can exhibit constant-current steps in their I-V characteristics when an AC signal is applied. This effect is due to phase locking of the Bloch oscillations associated with coherent tunneling of single Cooper pairs and is in many ways dual to the Shapiro steps, which appear at a constant voltage in arrays of larger junctions. To observe the current steps, the circuit needs to be embedded in a high-impedance environment, with an impedance significantly larger than the resistance quantum at the characteristic frequencies of the system. Such an impedance can be provided by high-ohmic on-chip thin-film resistors. Stray capacitances of these resistors will in reality result in a frequency-dependent impedance of the environment. We have performed circuit simulations to evaluate the influence of different electromagnetic environments on the step size as well as optimized the delivery of the AC drive. We have also examined the influence of noise in the on-chip resistors on the shape of the steps which can be observed in this system.