Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Superconductivity - Cryodetectors

TT 5.3: Talk

Monday, February 25, 2008, 12:15–12:30, H 3010

SQUID based readout and characterization of superconducting single photon detectors — •Alexander Kirste¹, Dietmar Drung¹, Jörn Beyer¹, Margret Peters¹, Thomas Schurig¹, Philipp Haas², Alexei Semenov², Heinz-Wilhelm Hübers², Konstantin Ilin³, Michael Siegel³, Rudolf Herrmann⁴, and Hans-Ulrich Müller⁴ — ¹Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin — ²German Aerospace Center (DLR), Rutherfordstr. 2, 12489 Berlin — ³University of Karlsruhe, Hertzstr. 16, 76187 Karlsruhe — ⁴Institut für angewandte Photonik, Rudower Chaussee 29, 12489 Berlin

We report on the readout and the characterization of nanostructured superconducting single photon detectors using SQUID arrays.

As the detectors allow photon counting with a modest energy resolution, it is important to use preamplifiers of high bandwidth and low noise. For this purpose SQUID arrays are a favourable choice as they are intrinsically wide-band and offer a low noise.

For the detector readout we apply SQUID arrays containing up to 640 single SQUIDs. These arrays have a white flux noise of 0.06 µΦ₀/Hz^1/2 at 4.2 K and a low dynamic impedance so that they are adequate to drive a following broadband microwave amplifier. Since the relevant time constants of the detector and the resulting duration of the voltage transients are intrinsically sub-ns, the SQUID is operated in AMP mode rather than in FLL mode. Using the internal preamplifier of the SQUID electronics XXF-1 with 50 MHz bandwidth, the voltage pulses at the output have a duration of 13 ns (FWHM).