| Records |
| Author |
Finkel, Matvey; Vachtomin, Yuriy; Antipov, Sereey; Drakinski, Vladimir; Kaurova, Natalia; Voronov, Boris; Goltsman, Greeory |
| Title |
Gain bandwidth and noise temperature of NbTiN HEB mixer |
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Conference Article |
| Year |
2003 |
Publication |
Proc. 14th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 14th Int. Symp. Space Terahertz Technol. |
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276-285 |
| Keywords |
NbTiN HEB mixer |
| Abstract |
We have determined that the gain bandwidth of phonon-cooled HEB mixer employing NbTiN films deposited on MgO layer over Si substrate is limited b y the escape of phonons to the substrate. The cut-off frequencies of 1 um long devices operating at T 71, based on 3.5 nm. 4 nm and 10 nm thick films amount to 400 Mk. 300 MHz, and 100 MHz, respectivel y . The gain bandwidth of 0.13 . um long devices fabricated from 3.5 nm thick film is larger and amounts to 0.8 GIL; at the optimal operating point and to 1.5 GIL: at larger bias. The increase of the gain bandwidth from 400 MHz up to 1.5 GH: with the change of bridge length is attributed to diffusion cooling. A double sideband noise temperature of 4000 K was obtained for heterodyne receiver utilizing pilot NbTiN HEB mixer (not optimized for normal state resistance) operating at the local oscillator frequency of 2.5 THz. |
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1500 |
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Verevkin, A.; Slysz, W.; Pearlman, A.; Zhang, J.; Sobolewski, R.; Okunev, O.; Korneev, A.; Kouminov, P.; Smirnov, K.; Chulkova, G.; Gol’tsman, G. N.; Currie, M. |
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Real-time GHz-rate counting of infrared photons using nanostructured NbN superconducting detectors |
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Conference Article |
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2003 |
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CLEO/QELS |
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CLEO/QELS |
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CThM8 |
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NbN SSPD; SNSPD; Infrared; Quantum detectors; Detectors; Photon counting; Quantum communications; Quantum cryptography; Single photon detectors; Superconductors |
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We demonstrate that our ultrathin, nanometer-width NbN superconducting single-photon detectors are capable of above 1-GHz-frequency, real-time counting of near-infrared photons. The measured system jitter of the detector is below 15 ps. |
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Optical Society of America |
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Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference |
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1517 |
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Verevkin, A.; Williams, C.; Gol’tsman, G. N.; Sobolewski, R.; Gilbert, G. |
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Single-photon superconducting detectors for practical high-speed quantum cryptography |
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Miscellaneous |
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2001 |
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OFCC/ICQI |
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OFCC/ICQI |
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Pa3 |
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NbN SSPD, SNSPD, QKD, quantum cryptography |
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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. |
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Rochester, New York |
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Optical Society of America |
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Optical Fiber Communication Conference and International Conference on Quantum Information |
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-- from poster session. |
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1544 |
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Maslennikova, Anna; Tretyakov, Ivan; Ryabchun, Sergey; Finkel, Matvey; Kaurova, Natalia; Voronov, Boris; Gol’tsman, Gregory |
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Gain bandwidth and noise temperature of NbN HEB mixers with simultaneous phonon and diffusion cooling |
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Abstract |
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2010 |
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Proc. 21th Int. Symp. Space Terahertz Technol. |
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Proc. 21th Int. Symp. Space Terahertz Technol. |
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218-219 |
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The space observatory Millimetron will be operating in the millimeter, sub-millimeter and infrared ranges using a 12-m cryogenic telescope in a single-dish mode, and as an interferometer with the space-earth and space-space baselines (the latter after the launch of the second identical space telescope). The observatory will allow performing astronomical observations with an unprecedented sensitivity (down to nJy level) in the single-dish mode, and observations with a high angular resolution in the interferometer mode. The total spectral range 20 μm – 2 cm is separated into 10 bands. HEB mixers with two cooling channels (diffusion and phonon) have been chosen to be the detectors of choice of the system covering the range from 1 THz to 6 THz as the best detectors in terahertz receivers. This type of HEB has already shown good work in the terahertz range. A gain bandwidth of 6 GHz at an LO frequency of 300 GHz and a noise temperature of 750 K at an LO frequency of 2.5 THz are the best values for HEB mixers with two cooling channels [1]. Theoretical estimations predict a bandwidth up to 12 GHz. Reaching such good result demands more systematic and thorough research. We present the results of the gain bandwidth and noise temperature measurements for superconducting hot- electron bolometer mixers with two cooling channels. These characteristics of the devices of lengths varying from 50 to 200 nm were measured for the purposes of Millimetron at frequencies of 600 GHz, 2.5 THz, and 3.8 THz. For gain bandwidth measurements we use two BWO’s operating at 600 GHz: one as the signal and the second as the LO. The noise temperature measurements were performed using a gas discharge laser as the LO and blackbodies at 77 K and 295 K as input signals. The devices studied consist of 3.5-nm-thick NbN bridges connected to thick (10 nm) high conductivity Au leads fabricated in situ. This method of fabricating devices has already proved promising by opening the diffusion cooling channel. [2] Fig. 1 shows a SEM photograph of a log-spiral antenna with an HEB at its apex. Fig. 1. Left: a SEM photograph of a log-spiral antenna with an HEB at its apex; right: a close-up of the HEB at the antenna apex. [1] S. A. Ryabchun, I. V. Tretyakov, M. I. Finkel, S. N. Maslennikov, N. S. Kaurova, V. A. Seleznev, B. M. Voronov, and G. N. Gol’tsman, NbN phonon-cooled hot-electron bolometer mixer with additional diffusion cooling, Proc. of the 20 th Int. Symp. Space. Technol., Charlottesville, Virginia, USA, April 20 – 22, 2009. 218[2] S. A. Ryabchun * , I. V. Tretyakov, M. I. Finkel, S. N. Maslennikov, N. S. Kaurova, V. A. Seleznev, B. M. Voronov and G. N. Goltsman, Fabrication and characterisation of NbN HEB mixers with in situ gold contacts, Proc. of the 19 th Int. Symp. Space. Technol., Groningen, The Netherlands, April 28-30, 2008 |
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1393 |
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Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol’tsman, G. N.; Demsar, J. |
| Title |
Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy |
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Miscellaneous |
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2011 |
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arXiv |
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NbN thin film, energy gap dynamics |
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Using time-domain Terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, \lambda = 1.1 +/- 0.1, which is in excellent agreement with theoretical estimates. |
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