Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 8: Posters Transport

TT 8.49: Poster

Freitag, 4. März 2005, 14:00–18:00, Poster TU C

Fluctuations in meander-like superconducting nanostructures — •Andreas Engel¹, Andreas Schilling¹, Alexei Semenov², Heinz-Wilhelm Hübers², Konstantin Il’in³, and Michael Siegel³ — ¹Physik Institut der Universität Zürich, Winterthurerstr. 190, 8057 Zürich, Schweiz — ²Deutsches Zentrum für Luft- und Raumfahrt, Rutherfordstr. 2, 12489 Berlin — ³Institut für Mikro- und Nanoelektronische Systeme, Universität Karlsruhe, Hertzstrasse 16, 76187 Karlsruhe

In superconducting films or wires thermal and quantum fluctuations play an increasingly important role, once one or more dimensions become of the order of the superconducting coherence length or less. Examples are thermal and quantum phase-slips in one-dimensional superconducting wires [1]. We experimentally studied fluctuations in NbN superconducting meanders 5 nm thick and 84 nm wide, biased with transport currents very close to the critical current I_c(T). In this operating regime such structures have been shown to be very fast and sensitive optical and near-infrared single-photon detectors [2]. The sensitivity is however limited by dark count events caused by superconducting fluctuations. We will discuss various fluctuation models and compare the temperature and current dependence with experimental results.

[1] C.N. Lau et al., Phys. Rev. Lett., 87, 217003 (2001), and refs. therein.

[2] A. Semenov et al., Eur. Phys. J. AP, 21, 171 (2003).