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TT: Fachverband Tiefe Temperaturen

TT 10: Poster Session: Superconductivity

TT 10.57: Poster

Montag, 14. März 2011, 14:00–18:00, P4

Spatially-Resolved Single-Photon Detection in NbN Nanowires — •Philipp Jung¹, Alexander Lukashenko¹, Alexander P. Zhuravel⁴, Stefan Wuensch^2,3, Matthias Hofherr², Konstantin Ilin², Michael Siegel², and Alexey V. Ustinov¹ — ¹Physikalisches Institut, Karlsruher Institut für Technologie, Karlsruhe, Germany — ²Institut für Mikro- und Nanoelektronische Systeme, Karlsruher Institut für Technologie, Karlsruhe, Germany — ³Supported by the DFG-Center for Functional Nanostructures — ⁴B. Verkin Institute for Low Temperature Physics & Engineering, Kharkov, Ukraine

We are investigating the mechanism of the single photon photoresponse in superconducting nanowires patterned from NbN thin-films on sapphire substrate. Current-biased close to their critical current, these nanowires are sensitive to small disturbances such as the absorption of a photon and are therefore used as single-photon detectors.

Although previous experiments on straight wires have shown their local critical currents to be quite inhomogeneous due to the existence of grain boundaries, meander shaped nanowire detectors exhibit a comparatively homogeneous spatial pattern of photon detection efficiency. To gain a deeper understanding of the relation between the local photon detection efficiency and the local critical current we are going to present comparative measurements of these two quantities acquired using a low temperature laser scanning microscope as well as a comparison of our results with existing theoretical predictions.