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Author Lobanov, Y.; Tong, E.; Blundell, R.; Hedden, A.; Voronov, B.; Gol'tsman, G. doi  openurl
  Title Large-signal frequency response of an HEB mixer: from 300 MHz to terahertz Type Journal Article
  Year 2011 Publication (up) IEEE Trans. Appl. Supercond. Abbreviated Journal  
  Volume 21 Issue 3 Pages 628-631  
  Keywords waveguide NbN HEB mixers  
  Abstract We present a study of the large signal frequency response of an HEB mixer over a wide frequency range. In our experiments, we have subjected the HEB mixer to incident electromagnetic radiation from 0.3 GHz to 1 THz. The mixer element is an NbN film deposited on crystalline quartz. The mixer chip is mounted in a waveguide cavity, coupled to free space with a diagonal horn. At microwave frequencies, electromagnetic radiation is applied through the coaxial bias port of the mixer block. At higher frequencies the input signal passes via the diagonal horn feed. At each frequency, the incident power is varied and a family of I-V curves is recorded. From the curves we identify 3 distinct regimes of operation of the mixer separated by the phonon relaxation frequency and the superconducting energy gap frequency observed at about 3 GHz and 660 GHz respectively. In this paper, we will present observed curves and discuss the results of our experiment.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 719  
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Author Lobanov, Y.V.; Tong, C.-Y.E.; Hedden, A.S.; Blundell, R.; Voronov, B.M.; Gol'tsman, G.N. doi  openurl
  Title Direct measurement of the gain and noise bandwidths of HEB mixers Type Journal Article
  Year 2011 Publication (up) IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 21 Issue 3 Pages 645-648  
  Keywords waveguide NbN HEB mixers  
  Abstract The intermediate frequency (IF) bandwidth of a hot electron bolometer (HEB) mixer is an important parameter of the mixer, in that it helps to determine its suitability for a given application. With the availability of wideband low noise amplifiers, it is simple to measure the performance of an HEB mixer over a wide range of IF at a fixed LO frequency using the standard Y-factor method. This in-situ method allows us to measure both the gain and noise bandwidths simultaneously. We have also measured mixer output impedance with a vector network analyser. Intrinsic time constant has been extracted from the impedance data and compared to the mixer's bandwidths determined from receiver Y-factor measurement.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 720  
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Author Kawakami, A; Saito, S.; Hyodo, M. openurl 
  Title Fabrication of nano-antennas for superconducting Infrared detectors Type Journal Article
  Year 2011 Publication (up) IEEE Trans. Appl. Supercond. Abbreviated Journal  
  Volume 21 Issue 3 Pages 632-635  
  Keywords optical antennas, NbN/MgO/NbN/TiN/Al HEB, dipole antennas, IR, infrared  
  Abstract To improve the response performance of superconducting infrared detectors, we have developed a fabrication process for nano-antennas. A nano-antenna consists of a dipole antenna, and a superconducting thin film strip placed in the antenna's center. By measuring the transition temperature of the superconducting strips, we confirmed that their superconductivity maintained a good condition after the nano-antenna fabrication process. We also evaluated nano-antenna characteristics using Fourier transform infrared spectroscopy. The evaluated antenna length and width were respectively set at around 2400 nm and 400 nm, and the antennas were placed at intervals of several micrometers around the area of 1 mm2 . In an evaluation of spectral transmission characteristics, clear absorption caused by antenna effects was observed at around 1400 cm-1. High polarization dependencies were also observed.  
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  Notes Approved no  
  Call Number Serial 761  
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Author Galeazzi, Massimiliano openurl 
  Title Fundamental noise processes in TES devices Type Journal Article
  Year 2011 Publication (up) IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 21 Issue 3 Pages 267-271  
  Keywords TES, Johnson noise, phonon noise, excess noise, flux-flow noise, thermal fluctuation noise  
  Abstract Microcalorimeters and bolometers are noise-limited devices, therefore, a proper understanding of all noise sources is essential to predict and interpret their performance. In this paper, I review the fundamental noise processes contributing to Transition Edge Sensor (TES) microcalorimeters and bolometers and their effect on device performance. In particular, I will start with a simple, monolithic device model, moving to a more complex one involving discrete components, to finally move to today's more realistic, comprehensive model. In addition to the basic noise contribution (equilibrium Johnson noise and phonon noise), TES are significantly affected by extra noise, which is commonly referred to as excess noise. Different fundamental processes have been proposed and investigated to explain the origin of this excess noise, in particular near equilibrium non-linear Johnson noise, flux-flow noise, and internal thermal fluctuation noise. Experimental evidence shows that all three processes are real and contribute, at different levels, to the TES noise, although different processes become important at different regimes. It is therefore time to discard the term “excess noise” and consider these terms part of the “fundamental noise processes” instead.  
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  Notes Recommended by Klapwijk Approved no  
  Call Number Serial 914  
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Author Pentin, I. V.; Smirnov, A. V.; Ryabchun, S. A.; Gol’tsman, G. N.; Vaks, V. L.; Pripolzin, S. I.; Paveliev, D. G. url  doi
openurl 
  Title Heterodyne source of THz range based on semiconductor superlattice multiplier Type Conference Article
  Year 2011 Publication (up) IRMMW-THz Abbreviated Journal IRMMW-THz  
  Volume Issue Pages 1-2  
  Keywords NbN HEB mixer, superlattice  
  Abstract We present the results of our studies of the possibility of developing a heterodyne receiver incorporating a hot-electron bolometer mixer as the detector and a semiconductor superlattice multiplier driven by a reference synthesizer as the local oscillator. We observe that such a local oscillator offers enough power in the terahertz range to pump the HEB into the operating state.  
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  Notes Approved no  
  Call Number 6105209 Serial 1384  
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Author Lee, B. G.; Assefa, S.; Green, W. M. J.; Min Yang; Schow, C. L.; Jahnes, C. V.; Sheng Zhang; Singer, J.; Kopp, V. I.; Kash, J. A.; Vlasov, Y. A. openurl 
  Title Multichannel high-bandwidth coupling of ultradense silicon photonic waveguide array to standard-pitch fiber array Type Journal Article
  Year 2011 Publication (up) J. Lightwave Technol. Abbreviated Journal  
  Volume 29 Issue 4 Pages 475-482  
  Keywords optical waveguides, from chiralphotonics  
  Abstract A multichannel tapered coupler interfacing standard 250-μm-pitch low-numerical-aperture (NA) polarization-maintaining fiber arrays with ultradense 20- μm-pitch high-NA silicon waveguides is designed and fabricated. The coupler is based on an array of 12 dual-core glass waveguides on 250-μ m pitch that are tapered to a 20- μm pitch, simultaneously providing both pitch and spot-size conversion. At the wide end, the inner core matches the NA and mode profile of standard single-mode fiber. When drawn and tapered, the inner core “vanishes” and the outer core, surrounded by the clad, matches the NA and mode profile of the on-chip photonic waveguide. Ultradense high-efficiency coupling to an array of Si photonic waveguides is demonstrated using a 12-channel polarization-maintaining-fiber pigtailed tapered coupler. Coupling to Si waveguides is facilitated using SiON spot-size converters integrated into the Si photonic IC to provide 2-3-μm mode field diameters compatible with the tapered coupler. The tapered coupler achieves <; 1 dB coupling losses to photonic waveguides. Furthermore, eight-channel coupling is shown with less than -35 dB crosstalk between channels. Finally, a 640-Gb/s wavelength-division-multiplexing signal is coupled into four waveguides occupying 80 μm of chip edge, providing 160-Gb/s per-channel bandwidths.  
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  Notes Approved no  
  Call Number Serial 849  
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Author Edlmayr, V.; Harzer, T. P.; Hoffmann, R.; Kiener, D.; Scheu, C.; Mitterer, C. openurl 
  Title Effects of thermal annealing on the microstructure of sputtered Al2O3 coatings Type Journal Article
  Year 2011 Publication (up) J. Vac. Sci. Technol. A Abbreviated Journal  
  Volume 29 Issue 4 Pages 8  
  Keywords Annealing  
  Abstract The morphology and microstructure of Al2O3 thin films deposited by pulsed direct current magnetron sputtering were studied in the as-grown state and after vacuum annealing at 1000 °C for 12 h using transmission electron microscopy. For the coating deposited under low ion bombardment conditions, the film consists of small γ- and/or δ-Al2O3 grains embedded in an amorphous matrix. The grain size at the region close to the interface to the substrate was much larger than that of the remaining layer. Growth of the γ-Al2O3 phase is promoted during annealing but no transformation to α-Al2O3 was detected. For high-energetic growth conditions, clear evidence for γ-Al2O3 formation was found in the upper part of the coating with grain size much larger than for low-energetic growth, but the film was predominately amorphous at the interface region. Annealing resulted in the transformation of γ-Al2O3 to α-Al2O3, while the mainly amorphous part crystallized to γ-Al2O3.  
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  Notes Annealing Approved no  
  Call Number RPLAB @ gujma @ Serial 693  
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Author Marsili, Francesco; Najafi, Faraz; Dauler, Eric; Bellei, Francesco; Hu, Xiaolong; Csete, Maria; Molnar, Richard J.; Berggren, Karl K. openurl 
  Title Single-photon detectors based on ultranarrow superconducting nanowires Type Journal Article
  Year 2011 Publication (up) Nano Letters Abbreviated Journal Nano Lett.  
  Volume 11 Issue 5 Pages 2048–2053  
  Keywords SNSPD  
  Abstract We report efficient single-photon detection (η = 20% at 1550 nm wavelength) with ultranarrow (20 and 30 nm wide) superconducting nanowires, which were shown to be more robust to constrictions and more responsive to 1550 nm wavelength photons than standard superconducting nanowire single-photon detectors, based on 90 nm wide nanowires. We also improved our understanding of the physics of superconducting nanowire avalanche photodetectors, which we used to increase the signal-to-noise ratio of ultranarrow-nanowire detectors by a factor of 4, thus relaxing the requirements on the read-out circuitry and making the devices suitable for a broader range of applications.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 659  
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Author Mitin, Vladimir; Antipov, Andrei; Sergeev, Andrei; Vagidov, Nizami; Eason, David; Strasser, Gottfried openurl 
  Title Quantum Dot Infrared Photodetectors: Photoresponse Enhancement Due to Potential Barriers Type Journal Article
  Year 2011 Publication (up) Nanoscale Research Letters Abbreviated Journal Nanoscale res lett  
  Volume 6 Issue 1 Pages 6  
  Keywords Quantum dots; Infrared detectors; Photoresponse; Doping; Potential barriers; Capture processes  
  Abstract Potential barriers around quantum dots (QDs) play a key role in kinetics of photoelectrons. These barriers are always created, when electrons from dopants outside QDs fill the dots. Potential barriers suppress the capture processes of photoelectrons and increase the photoresponse. To directly investigate the effect of potential barriers on photoelectron kinetics, we fabricated several QD structures with different positions of dopants and various levels of doping. The potential barriers as a function of doping and dopant positions have been determined using nextnano3 software. We experimentally investigated the photoresponse to IR radiation as a function of the radiation frequency and voltage bias. We also measured the dark current in these QD structures. Our investigations show that the photoresponse increases ~30 times as the height of potential barriers changes from 30 to 130 meV.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 712  
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Author Antipov, Andrei; Bell, Matt; Yasar, Mesut; Mitin, Vladimir; Scharmach, William; Swihart, Mark; Verevkin, Aleksandr; Sergeev, Andrei openurl 
  Title Luminescence of colloidal CdSe/ZnS nanoparticles: high sensitivity to solvent phase transitions Type Journal Article
  Year 2011 Publication (up) Nanoscale Research Letters Abbreviated Journal Nan. Res. Lett.  
  Volume 6 Issue Pages 7  
  Keywords  
  Abstract We investigate nanosecond photoluminescence processes in colloidal core/shell CdSe/ZnS nanoparticles dissolved in water and found strong sensitivity of luminescence to the solvent state. Several pronounced changes have been observed in the narrow temperature interval near the water melting point. First of all, the luminescence intensity substantially (approximately 50%) increases near the transition. In a large temperature scale, the energy peak of the photoluminescence decreases with temperature due to temperature dependence of the energy gap. Near the melting point, the peak shows N-type dependence with the maximal changes of approximately 30 meV. The line width increases with temperature and also shows N-type dependence near the melting point. The observed effects are associated with the reconstruction of ligands near the ice/water phase transition.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 722  
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Author Feresten, Nancy Laties; Thornton, Jennifer A.; Emmett, Jennifer; Lamichhane, Priyanka; Epstein, Lori; Kiesow, Annette; Olesin, Kate; Hill, Grace (eds) openurl 
  Title Everything: Rocks and Minerals Type Book Whole
  Year 2011 Publication (up) Nat. Geogr. Partners Abbreviated Journal  
  Volume Issue Pages 1-64  
  Keywords children  
  Abstract  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor Feresten, Nancy Laties; Thornton, Jennifer A.; Emmett, Jennifer; Lamichhane, Priyanka; Epstein, Lori; Kiesow, Annette; Olesin, Kate; Hill, Grace  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1146  
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Author Peruzzo, Alberto; Laing, Anthony; Politi, Alberto; Rudolph, Terry; O'Brien, Jeremy L. openurl 
  Title Multimode quantum interference of photons in multiport integrated devices Type Journal Article
  Year 2011 Publication (up) Nature Communications Abbreviated Journal Nat. Comm.  
  Volume 2 Issue 224 Pages 6  
  Keywords fromIPMRAS  
  Abstract Photonics is a leading approach in realizing future quantum technologies and recently, optical waveguide circuits on silicon chips have demonstrated high levels of miniaturization and performance. Multimode interference (MMI) devices promise a straightforward implementation of compact and robust multiport circuits. Here, we show quantum interference in a 2×2 MMI coupler with visibility of V=95.6+/-0.9%. We further demonstrate the operation of a 4×4 port MMI device with photon pairs, which exhibits complex quantum interference behaviour. We have developed a new technique to fully characterize such multiport devices, which removes the need for phase-sensitive measurements and may find applications for a wide range of photonic devices. Our results show that MMI devices can operate in the quantum regime with high fidelity and promise substantial simplification and concatenation of photonic quantum circuits.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 763  
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Author Ikuta, Rikizo; Kusaka, Yoshiaki; Kitano, suyoshi; Kato, Hiroshi; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki openurl 
  Title Wide-band quantum interface for visible-totelecommunication wavelength conversion Type Journal Article
  Year 2011 Publication (up) Nature Communications Abbreviated Journal Nat. Comm.  
  Volume 2 Issue Pages 5  
  Keywords fromIPMRAS  
  Abstract Although near-infrared photons in telecommunication bands are required for long-distance quantum communication, various quantum information tasks have been performed by using visible photons for the past two decades. Recently, such visible photons from diverse media including atomic quantum memories have also been studied. Optical frequency down-conversion from visible to telecommunication bands while keeping the quantum states is thus required for bridging such wavelength gaps. Here we report demonstration of a quantum interface of frequency down-conversion from visible to telecommunication bands by using a nonlinear crystal, which has a potential to work over wide bandwidths, leading to a high-speed interface of frequency conversion. We achieved the conversion of a picosecond visible photon at 780 nm to a 1,522-nm photon, and observed that the conversion process retained entanglement between the down-converted photon and another photon.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 764  
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Author Crespi, Andrea; Ramponi, Roberta; Osellame, Roberto; Sansoni, Linda; Bongioanni, Irene; Sciarrino, Fabio; Vallone, Giuseppe; Mataloni, Paolo openurl 
  Title Integrated photonic quantum gates for polarization qubits Type Journal Article
  Year 2011 Publication (up) Nature Communications Abbreviated Journal Nat. Comm.  
  Volume 2 Issue 566 Pages 6  
  Keywords fromIPMRAS  
  Abstract The ability to manipulate quantum states of light by integrated devices may open new perspectives both for fundamental tests of quantum mechanics and for novel technological applications. However, the technology for handling polarization-encoded qubits, the most commonly adopted approach, is still missing in quantum optical circuits. Here we demonstrate the first integrated photonic controlled-NOT (CNOT) gate for polarization-encoded qubits. This result has been enabled by the integration, based on femtosecond laser waveguide writing, of partially polarizing beam splitters on a glass chip. We characterize the logical truth table of the quantum gate demonstrating its high fidelity to the expected one. In addition, we show the ability of this gate to transform separable states into entangled ones and vice versa. Finally, the full accessibility of our device is exploited to carry out a complete characterization of the CNOT gate through a quantum process tomography.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 765  
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Author Berlín, Guido; Brassard, Gilles; Bussières, Félix; Godbout, Nicolas; Slater, Joshua A.; Tittel, Wolfgang openurl 
  Title Experimental loss-tolerant quantum coin flipping Type Journal Article
  Year 2011 Publication (up) Nature Communications Abbreviated Journal Nat. Comm.  
  Volume 2 Issue 561 Pages 7  
  Keywords fromIPMRAS  
  Abstract Coin flipping is a cryptographic primitive in which two distrustful parties wish to generate a random bit to choose between two alternatives. This task is impossible to realize when it relies solely on the asynchronous exchange of classical bits: one dishonest player has complete control over the final outcome. It is only when coin flipping is supplemented with quantum communication that this problem can be alleviated, although partial bias remains. Unfortunately, practical systems are subject to loss of quantum data, which allows a cheater to force a bias that is complete or arbitrarily close to complete in all previous protocols and implementations. Here we report on the first experimental demonstration of a quantum coin-flipping protocol for which loss cannot be exploited to cheat better. By eliminating the problem of loss, which is unavoidable in any realistic setting, quantum coin flipping takes a significant step towards real-world applications of quantum communication.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 766  
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