|
|
Slysz W, Wegrzecki M, Bar J, Grabiec P, Gorska M, Rieger E, et al. Fiber-coupled NbN superconducting single-photon detectors for quantum correlation measurements. In: Dusek M, Hillery MS, Schleich WP, Prochazka I, Migdall AL, Pauchard A, editors. Proc. SPIE. Vol 6583. Spie; 2007. 65830J (1 to 11).
Abstract: We have fabricated fiber-coupled superconducting single-photon detectors (SSPDs), designed for quantum-correlationtype experiments. The SSPDs are nanostructured ( 100-nm wide and 4-nm thick) NbN superconducting meandering stripes, operated in the 2 to 4.2 K temperature range, and known for ultrafast and efficient detection of visible to nearinfrared photons with almost negligible dark counts. Our latest devices are pigtailed structures with coupling between the SSPD structure and a single-mode optical fiber achieved using a micromechanical photoresist ring placed directly over the meander. The above arrangement withstands repetitive thermal cycling between liquid helium and room temperature, and we can reach the coupling efficiency of up to 33%. The system quantum efficiency, measured as the ratio of the photons counted by SSPD to the total number of photons coupled into the fiber, in our early devices was found to be around 0.3 % and 1% for 1.55 &mgr;m and 0.9 &mgr;m photon wavelengths, respectively. The photon counting rate exceeded 250 MHz. The receiver with two SSPDs, each individually biased, was placed inside a transport, 60-liter liquid helium Dewar, assuring uninterrupted operation for over 2 months. Since the receiver’s optical and electrical connections are at room temperature, the set-up is suitable for any applications, where single-photon counting capability and fast count rates are desired. In our case, it was implemented for photon correlation experiments. The receiver response time, measured as a second-order photon cross-correlation function, was found to be below 400 ps, with timing jitter of less than 40 ps.
|
|
|
|
Sclafani M, Marksteiner M, Keir FML, Divochiy A, Korneev A, Semenov A, et al. Sensitivity of a superconducting nanowire detector for single ions at low energy. Nanotechnol. 2012;23(6):065501 (1 to 5).
Abstract: We report on the characterization of a superconducting nanowire detector for ions at low kinetic energies. We measure the absolute single-particle detection efficiency eta and trace its increase with energy up to eta = 100%. We discuss the influence of noble gas adsorbates on the cryogenic surface and analyze their relevance for the detection of slow massive particles. We apply a recent model for the hot-spot formation to the incidence of atomic ions at energies between 0.2 and 1 keV. We suggest how the differences observed for photons and atoms or molecules can be related to the surface condition of the detector and we propose that the restoration of proper surface conditions may open a new avenue for SSPD-based optical spectroscopy on molecules and nanoparticles.
|
|
|
|
Semenov AD, Hübers H-W, Gol’tsman GN, Smirnov K. Superconducting quantum detector for astronomy and X-ray spectroscopy. In: Pekola J, Ruggiero B, Silvestrini P, editors. Proc. Int. Workshop on Supercond. Nano-Electronics Devices. : Springer; 2002. p. 201–10.
Abstract: We propose the novel concept of ultra-sensitive energy-dispersive superconducting quantum detectors prospective for applications in astronomy and X-ray spectroscopy. Depending on the superconducting material and operation conditions, such detector may allow realizing background limited noise equivalent power 10−21 W Hz−1/2 in the terahertz range when exposed to 4-K background radiation or counting of 6-keV photon with almost 10—4 energy resolution. Planar layout and relatively simple technology favor integration of elementary detectors into a detector array.
|
|
|
|
Verevkin AA, Zhang J, Slysz W, Sobolewski R, Lipatov AP, Okunev O, et al. Superconducting single-photon detectors for GHz-rate free-space quantum communications. In: Ricklin JC, Voelz DG, editors. Proc. SPIE. Vol 4821. SPIE; 2002. p. 447–54.
Abstract: We report our studies on the performance of new NbN ultrathin-film superconducting single-photon detectors (SSPDs). Our SSPDs exhibit experimentally measured quantum efficiencies from 5% at wavelength λ = 1550 nm up to 10% at λ = 405 nm, with exponential, activation-energy-type spectral sensitivity dependence in the 0.4-μm – 3-μm wavelength range. Using a variable optical delay setup, we have shown that our NbN SSPDs can resolve optical photons with a counting rate up to 10 GHz, presently limited by the read-out electronics. The measured device jitter was below 35 ps under optimum biasing conditions. The extremely high photon counting rate, together with relatively high (especially for λ > 1 μm) quantum efficiency, low jitter, and very low dark counts, make NbN SSPDs very promising for free-space communications and quantum cryptography.
|
|
|
|
Verevkin A, Williams C, Gol’tsman GN, Sobolewski R, Gilbert G. Single-photon superconducting detectors for practical high-speed quantum cryptography. Optical Society of America; 2001.
Abstract: We have developed an ultrafast superconducting single-photon detector with negligible dark counting rate. The detector is based on an ultrathin, submicron-wide NbN meander-type stripe and can detect individual photons in the visible to near-infrared wavelength range at a rate of at least 10 Gb/s. The above counting rate allows us to implement the NbN device to unconditionally secret quantum key distRochester, New Yorkribution in a practical, high-speed system using real-time Vernam enciphering.
|
|
