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Author Ryabchun, Sergey; Tong, Cheuk-Yu Edward; Blundell, Raymond; Gol'tsman, Gregory
Title Stabilization scheme for hot-electron bolometer receivers using microwave radiation Type Journal Article
Year 2009 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 19 Issue 1 Pages 14-19
Keywords HEB, mixer, Allan variance, stabilization, radiometer equation
Abstract (down) We present the results of a stabilization scheme for terahertz receivers based on NbN hot-electron bolometer (HEB) mixers that uses microwave radiation with a frequency much lower than the gap frequency of NbN to compensate for mixer current fluctuations. A feedback control loop, which actively controls the power level of the injected microwave radiation, has successfully been implemented to stabilize the operating point of the HEB mixer. This allows us to increase the receiver Allan time to 10 s and also improve the temperature resolution of the receiver by about 30% in the total power mode of operation.
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ISSN 1051-8223 ISBN Medium
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Notes Approved no
Call Number RPLAB @ lobanovyury @ Serial 559
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Author Kitaygorsky, J.; Zhang, J.; Verevkin, A.; Sergeev, A.; Korneev, A.; Matvienko, V.; Kouminov, P.; Smirnov, K.; Voronov, B.; Gol'tsman, G.; Sobolewski, R.
Title Origin of dark counts in nanostructured NbN single-photon detectors Type Journal Article
Year 2005 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 15 Issue 2 Pages 545-548
Keywords SSPD dark counts, SNSPD, dark counts rate
Abstract (down) We present our study of dark counts in ultrathin (3.5 to 10 nm thick), narrow (120 to 170 nm wide) NbN superconducting stripes of different lengths. In experiments, where the stripe was completely isolated from the outside world and kept at temperature below the critical temperature Tc, we detected subnanosecond electrical pulses associated with the spontaneous appearance of the temporal resistive state. The resistive state manifested itself as generation of phase-slip centers (PSCs) in our two-dimensional superconducting stripes. Our analysis shows that not far from Tc, PSCs have a thermally activated nature. At lowest temperatures, far below Tc, they are created by quantum fluctuations.
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Notes Approved no
Call Number Serial 1057
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Author Korneev, A.; Matvienko, V.; Minaeva, O.; Milostnaya, I.; Rubtsova, I.; Chulkova, G.; Smirnov, K.; Voronov, V.; Gol’tsman, G.; Slysz, W.; Pearlman, A.; Verevkin, A.; Sobolewski, R.
Title Quantum efficiency and noise equivalent power of nanostructured, NbN, single-photon detectors in the wavelength range from visible to infrared Type Journal Article
Year 2005 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 15 Issue 2 Pages 571-574
Keywords NbN SSPD, SNSPD, QE, NEP
Abstract (down) We present our studies on the quantum efficiency (QE) and the noise equivalent power (NEP) of the latest-generation, nanostructured, superconducting, single-photon detectors (SSPDs) in the wavelength range from 0.5 to 5.6 /spl mu/m, operated at temperatures in the 2.0- to 4.2-K range. Our detectors are designed as 4-nm-thick and 100-nm-wide NbN meander-shaped stripes, patterned by electron-beam lithography and cover a 10/spl times/10-/spl mu/m/sup 2/ active area. The best-achieved QE at 2.0 K for 1.55-/spl mu/m photons is 17%, and QE for 1.3-/spl mu/m infrared photons reaches its saturation value of /spl sim/30%. The SSPD NEP at 2.0 K is as low as 5/spl times/10/sup -21/ W/Hz/sup -1/2/. Our nanostructured SSPDs, operated at 2.0 K, significantly outperform their semiconducting counterparts, and, together with their GHz counting rate and picosecond timing jitter, they are devices-of-choice for practical quantum key distribution systems and free-space (even interplanetary) quantum optical communications.
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ISSN 1558-2515 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1467
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Author Samsonova, A. S.; Zolotov, P. I.; Baeva, E. M.; Lomakin, A. I.; Titova, N. A.; Kardakova, A. I.; Goltsman, G. N.
Title Signatures of surface magnetic disorder in niobium films Type Journal Article
Year 2021 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 31 Issue 5 Pages 1-5
Keywords Nb films
Abstract (down) We present our studies on the evolution of the normal and superconducting properties with thickness of thin Nb films with a low level of non-magnetic disorder ( kFl≈150 for the thickest film in the set). The analysis of the superconducting behavior points to the presence of magnetic moments, hidden in the native oxide on the surface of Nb films. Using the Abrikosov-Gorkov theory, we obtain the density of surface magnetic moments of 1013 cm −2 , which is in agreement with the previously reported data for Nb films.
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ISSN 1051-8223 ISBN Medium
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Notes Approved no
Call Number Serial 1792
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Author Kitaygorsky, J.; Komissarov, I.; Jukna, A.; Pan, D.; Minaeva, O.; Kaurova, N.; Divochiy, A.; Korneev, A.; Tarkhov, M.; Voronov, B.; Milostnaya, I.; Gol'tsman, G.; Sobolewski, R.R.
Title Dark counts in nanostructured nbn superconducting single-photon detectors and bridges Type Journal Article
Year 2007 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 17 Issue 2 Pages 275-278
Keywords SSPD; SNSPD
Abstract (down) We present our studies on dark counts, observed as transient voltage pulses, in current-biased NbN superconducting single-photon detectors (SSPDs), as well as in ultrathin (~4 nm), submicrometer-width (100 to 500 nm) NbN nanobridges. The duration of these spontaneous voltage pulses varied from 250 ps to 5 ns, depending on the device geometry, with the longest pulses observed in the large kinetic-inductance SSPD structures. Dark counts were measured while the devices were completely isolated (shielded by a metallic enclosure) from the outside world, in a temperature range between 1.5 and 6 K. Evidence shows that in our two-dimensional structures the dark counts are due to the depairing of vortex-antivortex pairs caused by the applied bias current. Our results shed some light on the vortex dynamics in 2D superconductors and, from the applied point of view, on intrinsic performance of nanostructured SSPDs.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1051-8223 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1248
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