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25 March 2005 Advanced nanostructured optical NbN single-photon detector operated at 2.0 K
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We present our studies on quantum efficiency (QE), dark counts, and noise equivalent power (NEP) of the latest generation of nanostructured NbN superconducting single-photon detectors (SSPDs) operated at 2.0 K. Our SSPDs are based on 4 nm-thick NbN films, patterned by electron beam lithography as highly-uniform 100÷120-nm-wide meander-shaped stripes, covering the total area of 10x10 μm2 with the meander filling factor of 0.7. Advances in the fabrication process and low-temperature operation lead to QE as high as ~30-40% for visible-light photons (0.56 μm wavelength)-the saturation value, limited by optical absorption of the NbN film. For 1.55 μm photons, QE was ~20% and decreased exponentially with the wavelength reaching ~0.02% at the 5-μm wavelength. Being operated at 2.0-K temperature the SSPDs revealed an exponential decrease of the dark count rate, what along with the high QE, resulted in the NEP as low as 5x10-21 W/Hz-1/2, the lowest value ever reported for near-infrared optical detectors. The SSPD counting rate was measured to be above 1 GHz with the pulse-to-pulse jitter below 20 ps. Our nanostructured NbN SSPDs operated at 2.0 K significantly outperform their semiconducting counterparts and find practical applications ranging from noninvasive testing of CMOS VLSI integrated circuits to ultrafast quantum communications and quantum cryptography.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gregory Goltsman, Alexander Korneev, Olga Minaeva, Inna Rubtsova, Galina Chulkova, Irina Milostnaya, Konstantin Smirnov, Boris Voronov, Andrey Petrovich Lipatov, Aaron J. Pearlman, A. Cross, Wojtek Slysz, Alexander Andreevich Verevkin, and Roman Sobolewski "Advanced nanostructured optical NbN single-photon detector operated at 2.0 K", Proc. SPIE 5732, Quantum Sensing and Nanophotonic Devices II, (25 March 2005);

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