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| Author | Bason, Mark G.; Viteau, Matthieu; Malossi, Nicola; Huillery, Paul; Arimondo, Ennio; Ciampini, Donatella; Fazio, Rosario; Giovannetti, Vittorio; Mannella, Riccardo; Morsch, Oliver | ||||
| Title | High-fidelity quantum driving | Type | Journal Article | ||
| Year | 2012 | Publication | Nature Physics | Abbreviated Journal | Nat. Phys. |
| Volume | 8 | Issue | 2 | Pages | 147-152 |
| Keywords | fromIPMRAS | ||||
| Abstract | Accurately controlling a quantum system is a fundamental requirement in quantum information processing and the coherent manipulation of molecular systems. The ultimate goal in quantum control is to prepare a desired state with the highest fidelity allowed by the available resources and the experimental constraints. Here we experimentally implement two optimal high-fidelity control protocols using a two-level quantum system comprising Bose-Einstein condensates in optical lattices. The first is a short-cut protocol that reaches the maximum quantum-transformation speed compatible with the Heisenberg uncertainty principle. In the opposite limit, we realize the recently proposed transitionless superadiabatic protocols in which the system follows the instantaneous adiabatic ground state nearly perfectly. We demonstrate that superadiabatic protocols are extremely robust against control parameter variations, making them useful for practical applications. | ||||
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| Notes | Approved | no | |||
| Call Number | RPLAB @ gujma @ | Serial | 816 | ||
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| Author | Shurakov, Alexander; Tong, Edward; Blundell, Raymond; Gol'tsman, Gregory | ||||
| Title | Microwave stabilization of HEB mixer by a microchip controller | Type | Conference Article | ||
| Year | 2012 | Publication | IEEE MTT-S international microwave symposium digest | Abbreviated Journal | |
| Volume | Issue | Pages | 1-3 | ||
| Keywords | HEB mixer stability, microwave injection, Allan variance, Allan time | ||||
| Abstract | The stability of a Hot Electron Bolometer (HEB) mixer can be improved by the use of microwave injection. In this article we report a refinement of this approach. We introduce a microchip controller to facilitate the implementation of the stabilization scheme, and demonstrate that the feedback loop effectively suppresses drifts in the HEB bias current, leading to an improvement in the receiver stability. The measured Allan time of the mixer's IF output power is increased to > 10 s. | ||||
| Address | Montreal, QC, Canada | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 857 | |||
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| Author | Henrich, D.; Dorner,S.; Hofherr, M.; Il'in, K.; Semenov, A.; Heintze, E.; Scheffler, M.; Dressel, M.; Siegel, M. | ||||
| Title | Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content | Type | Journal Article | ||
| Year | 2012 | Publication | Abbreviated Journal | J. Appl. Phys. | |
| Volume | 112 | Issue | Pages | ||
| Keywords | SSPD, SNSPD, magnetron sputtering, spectrum, NbN film, nitrogen concentration | ||||
| Abstract | The spectral detection efficiency and the dark count rate of superconducting nanowire single-photon detectors (SNSPD) have been studied systematically on detectors made from thin NbN films with different chemical compositions. Reduction of the nitrogen content in the 4 nm thick NbN films results in a decrease of the dark count rates more than two orders of magnitude and in a red shift of the cut-off wavelength of the hot-spot SNSPD response. The observed phenomena are explained by an improvement of uniformity of NbN films that has been confirmed by a decrease of resistivity and an increase of the ratio of the measured critical current to the depairing current. The latter factor is considered as the most crucial for both the cut-off wavelength and the dark count rates of SNSPD. Based on our results we propose a set of criteria for material properties to optimize SNSPD in the infrared spectral region. VC 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4757625] |
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| Corporate Author | D. Henrich, S. Dorner, M. Hofherr, K. Il'in, A. Semenov, E. Heintze, M. Scheffler, M. Dressel, M. Siegel | Thesis | |||
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| Language | English | Summary Language | Original Title | Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content | |
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| Call Number | RPLAB @ seleznev @ | Serial | 877 | ||
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| Author | Inderbitzin, K.; Engel, A.; Schilling, A.; Il'in, K.; Siegel, M. | ||||
| Title | An ultra-fast superconducting Nb nanowire single-photon detector for soft x-rays | Type | Journal Article | ||
| Year | 2012 | Publication | Abbreviated Journal | Appl. Phys. Lett. | |
| Volume | 101 | Issue | Pages | ||
| Keywords | SSPD, SNSPD, x-ray, Nb | ||||
| Abstract | Although superconducting nanowire single-photon detectors (SNSPDs) are well studied regarding the detection of infrared/optical photons and keV-molecules, no studies on continuous x-ray photon counting by thick-film detectors have been reported so far. We fabricated a 100 nm thick niobium x-ray SNSPD (an X-SNSPD) and studied its detection capability of photons with keV-energies in continuous mode. The detector is capable to detect photons even at reduced bias currents of 0.4%, which is in sharp contrast to optical thin-film SNSPDs. No dark counts were recorded in extended measurement periods. Strikingly, the signal amplitude distribution depends significantly on the photon energy spectrum.VC |
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| Notes | Approved | no | |||
| Call Number | RPLAB @ seleznev @ | Serial | 878 | ||
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| Author | Julia Toussaint, Roman Grüner, Marco Schubert, Torsten May, Hans-Georg Meyer, Benjamin Dietzek, Jürgen Popp, Matthias Hofherr, Matthias Arndt, Dagmar Henrich, Konstantin Il'in, and Michael Siegel | ||||
| Title | Superconducting single-photon counting system for optical experiments requiring time-resolution in the picosecond range | Type | Journal Article | ||
| Year | 2012 | Publication | Abbreviated Journal | AIP REVIEW OF SCIENTIFIC INSTRUMENTS | |
| Volume | 83 | Issue | Pages | ||
| Keywords | SSPD, picosecond, time-resolution | ||||
| Abstract | We have developed a cryogenic measurement system for single-photon counting, which can be used in optical experiments requiring high time resolution in the picosecond range. The system utilizes niobium nitride superconducting nanowire single-photon detectors which are integrated in a timecorrelated single-photon counting (TCSPC) setup. In this work, we describe details of the mechanical design, the electrical setup, and the cryogenic optical components. The performance of the complete system in TCSPC mode is tentatively benchmarked using 140 fs long laser pulses at a repetition frequency of 75MHz. Due to the high temporal stability of these pulses, the measured time resolution of 35 ps (FWHM) is limited by the timing jitter of the measurement system. The result was crosschecked in a Coherent Anti-stokes Raman Scattering (CARS) setup, where scattered pulses from a β-barium borate crystal have been detected with the same time resolution. |
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| Call Number | RPLAB @ seleznev @ | Serial | 885 | ||
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| Author | Vercruyssen, N.; Verhagen, T. G. A.; Flokstra, M. G.; Pekola, J. P.; Klapwijk, T. M. | ||||
| Title | Evanescent states and nonequilibrium in driven superconducting nanowires | Type | Journal Article | ||
| Year | 2012 | Publication | Phys. Rev. B | Abbreviated Journal | Phys. Rev. B |
| Volume | 85 | Issue | Pages | 224503(1-10) | |
| Keywords | Al HEB, Al superconducting nanowire, global state, bimodal state, quasiclassical kinetic equations, Usadel equation | ||||
| Abstract | We study the nonlinear response of current transport in a superconducting diffusive nanowire between normal reservoirs. We demonstrate theoretically and experimentally the existence of two different superconducting states appearing when the wire is driven out of equilibrium by an applied bias, called the global and bimodal superconducting states. The different states are identified by using two-probe measurements of the wire, and measurements of the local density of states with tunneling probes. The analysis is performed within the framework of the quasiclassical kinetic equations for diffusive superconductors. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 898 | |||
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| Author | Pütz, P.; Honingh, C. E.; Jacobs, K.; Justen, M.; Schultz, M.; Stutzki, J. | ||||
| Title | Terahertz hot electron bolometer waveguide mixers for GREAT | Type | Journal Article | ||
| Year | 2012 | Publication | Astron. Astrophys. | Abbreviated Journal | A&A |
| Volume | 542 | Issue | Pages | L2 | |
| Keywords | HEB mixer, applications | ||||
| Abstract | Context. Supplementing the publications based on the first-light observations with the German REceiver for Astronomy at Terahertz frequencies (GREAT) on SOFIA, we present background information on the underlying heterodyne detector technology. This Letter complements the GREAT instrument Letter and focuses on the mixers itself. Aims. We describe the superconducting hot electron bolometer (HEB) detectors that are used as frequency mixers in the L1 (1400 GHz), L2 (1900 GHz), and M (2500 GHz) channels of GREAT. Measured performance of the detectors is presented and background information on their operation in GREAT is given. Methods. Our mixer units are waveguide-based and couple to free-space radiation via a feedhorn antenna. The HEB mixers are designed, fabricated, characterized, and flight-qualified in-house. We are able to use the full intermediate frequency bandwidth of the mixers using silicon-germanium multi-octave cryogenic low-noise amplifiers with very low input return loss. Results. Superconducting HEB mixers have proven to be practical and sensitive detectors for high-resolution THz frequency spectroscopy on SOFIA. We show that our niobium-titanium-nitride (NbTiN) material HEBs on silicon nitride (SiN) membrane substrates have an intermediate frequency (IF) noise roll-off frequency above 2.8 GHz, which does not limit the current receiver IF bandwidth. Our mixer technology development efforts culminate in the first successful operation of a waveguide-based HEB mixer at 2.5 THz and deployment for radioastronomy. A significant contribution to the success of GREAT is made by technological development, thorough characterization and performance optimization of the mixer and its IF interface for receiver operation on SOFIA. In particular, the development of an optimized mixer IF interface contributes to the low passband ripple and excellent stability, which GREAT demonstrated during its initial successful astronomical observation runs. |
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| Notes | Approved | no | |||
| Call Number | Serial | 907 | |||
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| Author | Rasulova, G. K.; Brunkov, P. N.; Pentin, I. V.; Egorov, A. Y.; Knyazev, D. A.; Andrianov, A. V.; Zakhar’in, A. O.; Konnikov, S. G.; Gol’tsman, G. N. | ||||
| Title | A weakly coupled semiconductor superlattice as a potential for a radio frequency modulated terahertz light emitter | Type | Journal Article | ||
| Year | 2012 | Publication | Appl. Phys. Lett. | Abbreviated Journal | Appl. Phys. Lett. |
| Volume | 100 | Issue | 13 | Pages | 131104 (1 to 4) |
| Keywords | semiconductor superlattice | ||||
| Abstract | The bolometer response to THz radiation from a weakly coupled GaAs/AlGaAs superlattice biased in the self-oscillations regime has been observed. The bolometer signal is modulated with the frequency equal to the fundamental frequency of superlattice self-oscillations. The frequency spectrum of the bolometer signal contains higher harmonics whose frequency is a multiple of fundamental frequency of self-oscillations. This work was supported by State Contracts Nos. 16.740.11.0044 and 16.552.11.7002 of Ministry of Education and Science of the Russian Federation. Structural characterization was made on the equipment of the Joint Research Centre «Material science and characterization in advanced technology» (Ioffe Institute, St. Petersburg, Russia). |
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| ISSN | 0003-6951 | ISBN | Medium | ||
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| Notes | Approved | no | |||
| Call Number | Serial | 1379 | |||
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| Author | D. Henrich, L. Rehm S. Dörner, M. Hofherr, K. Il'in, A. Semenov, and M. Siegel | ||||
| Title | Detection efficiency of a spiral-nanowire superconducting single-photon detector | Type | Journal Article | ||
| Year | 2012 | Publication | Abbreviated Journal | ||
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| Keywords | Critical current, Nanoscale devices, Superconducting photodetectors. | ||||
| Abstract | We investigate the detection efficiency of a spiral layout of a Superconducting Nanowire Single-Photon Detector (SNSPD). The design is less susceptible to the critical current reduction in sharp turns of the nanowire than the conventional meander design. Detector samples with different nanowire width from 300 to 100 nm are patterned from a 4 nm thick NbN film deposited on sapphire substrates. The critical current IC at 4.2 K for spiral, meander, and simple bridge structures is measured and compared. On the 100 nm wide samples, the detection efficiency is measured in the wavelength range 400-1700 nm and the cut-off wavelength of the hot-spot plateau is determined. In the optical range, the spiral detector reaches a detection efficiency of 27.6%, which is ~1.5 times the value of the meander. In the infrared range the detection efficiency is more than doubled. | ||||
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| Corporate Author | D. Henrich, L. Rehm S. Dörner, M. Hofherr, K. Il'in, A. Semenov, and M. Siegel | Thesis | |||
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| Notes | Approved | no | |||
| Call Number | RPLAB @ seleznev @ | Serial | 880 | ||
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| Author | Shurakov, A.; Seliverstov, S.; Kaurova, N.; Finkel, M.; Voronov, B.; Goltsman, G. | ||||
| Title | Input bandwidth of hot electron bolometer with spiral antenna | Type | Journal Article | ||
| Year | 2012 | Publication | IEEE Trans. THz Sci. Technol. | Abbreviated Journal | IEEE Trans. THz Sci. Technol. |
| Volume | 2 | Issue | 4 | Pages | 400-405 |
| Keywords | NbN HEB bolometers bandwidth, log-spiral antenna | ||||
| Abstract | We report the results of our study of the input bandwidth of hot electron bolometers (HEB) embedded into the planar log-spiral antenna. The sensitive element is made of the ultrathin superconducting NbN film patterned as a bridge at the feed of the antenna. The contacts between the antenna and a sensitive element are made from in situ deposited gold (i.e., deposited over NbN film without breaking vacuum), which gives high quality contacts and makes the response of the HEB at higher frequencies less affected by the RF loss. An accurate experimental spectroscopic procedure is demonstrated that leads to the confirmation of the wide ( 8 THz) bandwidth in this antenna coupled device. | ||||
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| ISSN | 2156-342X | ISBN | Medium | ||
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| Notes | Approved | no | |||
| Call Number | Serial | 1161 | |||
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