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Author Siddiqi, I.; Prober, D. E. url  doi
openurl 
  Title Nb–Au bilayer hot-electron bolometers for low-noise THz heterodyne detection Type Journal Article
  Year 2004 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 84 Issue 8 Pages 1404  
  Keywords HEB, mixers, dynamic range, saturation, LO power, local oscillator power, Nb  
  Abstract The sensitivity of present Nb diffusion-cooled hot-electron bolometer (HEB) mixers is not quantum limited, and can be improved by reducing the superconducting transition temperature TC. Lowering TC reduces thermal fluctuations, resulting in a decrease of the mixer noise temperature TM. However, lower TC mixers have reduced dynamic range and saturate more easily due to background noise. We present 30 GHz microwave measurements on a bilayer HEB system, Nb–Au, in which TC can be tuned with Au layer thickness to obtain the maximum sensitivity for a given noise background. These measurements are intended as a guide for the optimization of THz mixers. Using a Nb–Au mixer with TC = 1.6 K, we obtain TM = 50 K with 2 nW of local oscillator (LO) power. Good mixer performance is observed over a wide range of LO power and bias voltage and such a device should not exhibit saturation in a THz receiver.  
  Address  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-6951 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number (up) Serial 571  
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Author Barends, R.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M. openurl 
  Title Current-induced vortex unbinding in bolometer mixers Type Journal Article
  Year 2005 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 87 Issue Pages 263506 (1 to 3)  
  Keywords HEB mixer numerical model, HEB model, IV-curves, vortex-antivortex, Berezinskii–Kosterlitz–Thouless theory, diffusion cooling channel, diffusion channel, distributed HEB model, distributed model, self-heating effect, temperature profile  
  Abstract We present a description of the current-voltage characteristics of hot electron bolometers in terms of the current-dependent intrinsic resistive transition of NbN films. We find that, by including this current dependence, we can correctly predict the complete current-voltage characteristics, showing excellent agreement with measurements for both low and high bias and for small as well as large devices. It is assumed that the current dependence is due to vortex-antivortex unbinding as described in the Berezinskii–Kosterlitz–Thouless theory. The presented approach will be useful in guiding device optimization for noise and bandwidth.  
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  Notes Approved no  
  Call Number (up) Serial 604  
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Author Li, T. F.; Pashkin, Yu. A.; Astafiev, O.; Nakamura, Y.; Tsai, J. S.; Im, H. doi  openurl
  Title High-frequency metallic nanomechanical resonators Type Journal Article
  Year 2008 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 92 Issue Pages 043112(1)-043112(3)  
  Keywords nanomechanical resonator, polycrystalline metal films  
  Abstract We developed a technology to fabricate fully metallic doubly clamped beams working as nanomechanical resonators. Measured with a magnetomotive detection scheme, the beams, made of polycrystalline metal films, show as good quality as previously reported ones made of single crystal materials, such as Si, GaAs, AlN, and SiC. Our method is compatible with the conventional fabrication process for nanoscale electronic circuits and thus offers a possibility of easily integrating the beams into superconducting charge and flux qubits and single-electron transistors as well as coupling them to coplanar waveguide resonators.  
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  Series Editor Series Title Abbreviated Series Title  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number (up) Serial 621  
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Author Zhang, W.; Khosropanah, P.; Gao, J. R.; Kollberg, E. L.; Yngvesson, K. S.; Bansal, T.; Barends, R.; Klapwijk, T. M. openurl 
  Title Quantum noise in a terahertz hot electron bolometer mixer Type Journal Article
  Year 2010 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 96 Issue 11 Pages 111113-(1-3)  
  Keywords HEB mixer, quantum limit, quantum noise, vacuum box, THz, Terahertz  
  Abstract We have measured the noise temperature of a single, sensitive superconducting NbN hot electron bolometer (HEB) mixer in a frequency range from 1.6 to 5.3 THz, using a setup with all the key components in vacuum. By analyzing the measured receiver noise temperature using a quantum noise (QN) model for HEB mixers, we confirm the effect of QN. The QN is found to be responsible for about half of the receiver noise at the highest frequency in our measurements. The beta-factor (the quantum efficiency of the HEB) obtained experimentally agrees reasonably well with the calculated value.  
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  Notes Approved no  
  Call Number (up) Serial 624  
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Author Walther, Christoph; Scalari, Giacomo; Faist, Jerome; Beere, Harvey; Ritchie, David openurl 
  Title Low frequency terahertz quantum cascade laser operating from 1.6 to 1.8 THz Type Journal Article
  Year 2006 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 89 Issue Pages 231121(1-3)  
  Keywords QCL, 360 uW at 1.6 THz  
  Abstract The authors report a GaAs/Al0.1Ga0.9As quantum cascade laser based on a bound-to-continuum transition optimized for low frequency operation. High tunability of the gain curve is achieved by the Stark effect and laser emission is measured between 1.6 and 1.8 THz. Pulsed mode operation up to 95 K and continuous wave operation up to 80 K are reported. The dynamical range in current is as high as 43%.  
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  Notes Approved no  
  Call Number (up) Serial 629  
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Author Sekine, Norihiko; Hosako, Iwao openurl 
  Title Intensity modulation of terahertz quantum cascade lasers under external light injection Type Journal Article
  Year 2009 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 95 Issue Pages 201106(1-3)  
  Keywords QCL modulation, THz, terahertz  
  Abstract We investigated the light-current characteristics of terahertz (THz) quantum cascade lasers under external light injection, which excites interband transitions in the active materials. It was found that the amount of reduction in the THz power was constant for all injection currents above threshold, and the dependence of the reduction amount on the wavelength of the external light was observed to show a resonancelike feature. The dominant intensity modulation mechanism was found to be the loss change caused by interband transitions in the active region. Further, the effective coupling efficiency plays an important role in the intensity modulation.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number (up) Serial 630  
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Author Sprengers, J. P.; Gaggero, A.; Sahin, D.; Jahanmirinejad, S.; Frucci, G.; Mattioli, F.; Leoni, R.; Beetz, J.; Lermer, M.; Kamp, M.; Höfling, S.; Sanjines, R.; Fiore A. openurl 
  Title Waveguide superconducting single-photon detectors for integrated quantum photonic circuits Type Journal Article
  Year 2011 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 99 Issue 18 Pages 181110(1-3)  
  Keywords optical waveguides, waveguide SSPD  
  Abstract The monolithic integration of single-photon sources, passive optical circuits, and single-photon detectors enables complex and scalable quantum photonic integrated circuits, for application in linear-optics quantum computing and quantum communications. Here, we demonstrate a key component of such a circuit, a waveguide single-photon detector. Our detectors, based on superconducting nanowires on GaAs ridge waveguides, provide high efficiency (~0%) at telecom wavelengths, high timing accuracy (~0 ps), and response time in the ns range and are fully compatible with the integration of single-photon sources, passive networks, and modulators.  
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  Notes Approved no  
  Call Number (up) Serial 847  
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Author Il'in, K. S.; Lindgren, M.; Currie, M. A.; Semenov, D.; Gol'tsman, G. N.; Sobolewski, Roman; Cherednichenko, S. I.; Gershenzon, E. M. url  doi
openurl 
  Title Picosecond hot-electron energy relaxation in NbN superconducting photodetectors Type Journal Article
  Year 2000 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 76 Issue 19 Pages 2752-2754  
  Keywords NbN HEB detectors, two-temperature model, IF bandwidth  
  Abstract We report time-resolved characterization of superconducting NbN hot-electron photodetectors using an electro-optic sampling method. Our samples were patterned into micron-size microbridges from 3.5-nm-thick NbN films deposited on sapphire substrates. The devices were illuminated with 100 fs optical pulses, and the photoresponse was measured in the ambient temperature range between 2.15 and 10.6 K (superconducting temperature transition TC). The experimental data agreed very well with the nonequilibrium hot-electron, two-temperature model. The quasiparticle thermalization time was ambient temperature independent and was measured to be 6.5 ps. The inelastic electron–phonon scattering time Ï„e–ph tended to decrease with the temperature increase, although its change remained within the experimental error, while the phonon escape time Ï„es decreased almost by a factor of two when the sample was put in direct contact with superfluid helium. Specifically, Ï„e–ph and Ï„es, fitted by the two-temperature model, were equal to 11.6 and 21 ps at 2.15 K, and 10(±2) and 38 ps at 10.5 K, respectively. The obtained value of Ï„e–ph shows that the maximum intermediate frequency bandwidth of NbN hot-electron phonon-cooled mixers operating at TC can reach 16(+4/–3) GHz if one eliminates the bolometric phonon-heating effect.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-6951 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number (up) Serial 856  
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Author Kataoka, T; Kajikawa, K.; Kitagawa, J.; Kadoya, Y; Takemura, Y. openurl 
  Title Improved sensitivity of terahertz detection by GaAs photoconductive antennas excited at 1560 nm Type Journal Article
  Year 2010 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 97 Issue Pages 201110 (1-3)  
  Keywords photoconductive antenna (PCA)  
  Abstract The terahertz detection by photoconductive antennas (PCAs) based on low-temperature grown (LTG) GaAs with 1.5 μm pulse excitation was revisited. We found that the detection efficiency can be improved by a factor of 10 (20 dB) by reducing the excitation spot size and the gap length of the PCA, maintaining the low noise feature of the PCA on LTG GaAs. As a result, the signal-to-noise ratio higher than 50 dB was obtained at a reasonable incident power of 9.5 mW, suggesting that the scheme is promising for the detection of terahertz waves in practical time domain systems.  
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  Notes Approved no  
  Call Number (up) Serial 904  
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Author Gao, J. R.; Hovenier, J. N.; Yang, Z. Q.; Baselmans, J. J. A.; Baryshev, A.; Hajenius, M.; Klapwijk, T. M.; Adam, A. J. L.; Klaassen, T. O.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L. openurl 
  Title Terahertz heterodyne receiver based on a quantum cascade laser and a superconducting bolometer Type Journal Article
  Year 2005 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 86 Issue Pages 244104 (1 to 3)  
  Keywords HEB, QCL  
  Abstract We report the first demonstration of an all solid-stateheterodyne receiver that can be used for high-resolution spectroscopy above 2THz suitable for space-based observatories. The receiver uses a NbN superconducting hot-electron bolometer as mixer and a quantum cascade laser operating at 2.8THz as local oscillator. We measure a double sideband receiver noise temperature of 1400K at 2.8THz and 4.2K, and find that the free-running QCL has sufficient power stability for a practical receiver, demonstrating an unprecedented combination of sensitivity and stability.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number (up) Serial 905  
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