Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 49: Superconductivity: SQUIDs & Cryodetectors

TT 49.7: Talk

Wednesday, March 13, 2013, 18:30–18:45, H21

Effect of the wire geometry and an externally applied magnetic field on the detection efficiency of superconducting nanowire single-photon detectors — •Robert Lusche¹, Alexey Semenov¹, Heinz-Willhelm Hübers¹, Konstantin Ilin², Michael Siegel², Yuliya Korneeva³, Andrey Trifonov³, Alexander Korneev³, and Gregory Goltsman³ — ¹DLR, Institut für Planetenforschung, Berlin, Germany — ²Karlsruher Institut für Technologie — ³Moscow State Pedagogical University, Russia

The interest in single-photon detectors in the near-infrared wavelength regime for applications, e.g. in quantum cryptography has immensely increased in the last years. Superconducting nanowire single-photon detectors (SNSPD) already show quite reasonable detection efficiencies in the NIR which can even be further improved. Novel theoretical approaches including vortex-assisted photon counting state that the detection efficiency in the long wavelength region can be enhanced by the detector geometry and an applied magnetic field. We will present spectral measurements in the wavelength range from 350-2500nm of the detection efficiency of meander-type TaN and NbN SNSPD with varying nanowire line width from 80 to 250nm. Due to the used experimental setup we can accurately normalize the measured spectra and are able to extract the intrinsic detection efficiency (IDE) of our detectors. The results clearly indicate an improvement of the IDE depending on the wire width according to the theoretic models. Furthermore we experimentally found that the smallest detectable photon-flux can be increased by applying a small magnetic field to the detectors.