Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 23: Posters Superconductivity, Solids at Low Temperature

TT 23.54: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU D

Superconducting noise bolometer as a direct detector — •Alexei Semenov¹, Heinz-Wilhelm Hübers¹, Konstantin Ilin², Michael Siegel², and Andreas Engel³ — ¹DLR Institute of Planetary Research, Berlin — ²Institute of Micro- and Nanosystems, University of Karlsruhe — ³Institute of Physics, University of Zürich

An advantage of superconducting detectors is a much lower noise in comparison to their semiconductor counterparts. We have studied the magnitude and spectrum of electric noise in thin superconducting NbN nanostrips carrying a subcritical current. Analysis of the experimental data suggests that the noise appears due to fluctuations in the two-dimensional vortex gas below the Kosterlitz-Thouless phase transition. Basing on our understanding of the noise source, we proposed a novel detector concept. The novelty is the use of the noise, which generally hampers the performance of conventional detectors, as the physical quantity that itself senses radiation. Our detector is a meander line patterned from a superconducting thin film and connected to the terminals of a planar log-periodic antenna. The detector operates in the current-carrying superconducting state and exhibits the noise that changes under irradiation. At 4.2 K measured noise-equivalent power amounted at 10⁻¹⁴ W Hz^−1/2 and is likely to improve at lower temperatures.