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Hase, Muneaki; Katsuragawa, Masayuki; Constantinescu, Anca Monia; Petek, Hrvoje |
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Title |
Frequency comb generation at terahertz frequencies by coherent phonon excitation in silicon |
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Journal Article |
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2012 |
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Nature Photonics |
Abbreviated Journal |
Nat. Photon. |
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6 |
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243–247 |
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High-order nonlinear light–matter interactions in gases enable the generation of X-ray and attosecond light pulses, metrology and spectroscopy1. Optical nonlinearities in solid-state materials are particularly interesting for combining optical and electronic functions for high-bandwidth information processing2. Third-order nonlinear optical processes in silicon have been used to process optical signals with bandwidths greater than 1 GHz (ref. 2). However, fundamental physical processes for a silicon-based optical modulator in the terahertz bandwidth range have not yet been explored. Here, we demonstrate ultrafast phononic modulation of the optical index of silicon by irradiation with intense few-cycle femtosecond pulses. The anisotropic reflectivity modulation by the resonant Raman susceptibility at the fundamental frequency of the longitudinal optical phonon of silicon (15.6 THz) generates a frequency comb up to seventh order. All-optical >100 THz frequency comb generation is realized by harnessing the coherent atomic motion of the silicon crystalline lattice at its highest mechanical frequency. |
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RPLAB @ gujma @ |
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794 |
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Mineev, Vladimir P. |
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Title |
Superfluid helium: Order in disorder |
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Journal Article |
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2012 |
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Nature Physics |
Abbreviated Journal |
Nat. Phys. |
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8 |
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253–254 |
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Confining liquid 3He in porous silica aerogel prepared with strong anisotropy stabilizes a state of axial superfluidity. |
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RPLAB @ gujma @ |
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810 |
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Clerk, Aashish |
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Title |
Quantum phononics: To see a SAW |
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Journal Article |
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2012 |
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Nature Physics |
Abbreviated Journal |
Nat. Phys. |
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8 |
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4 |
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256-257 |
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Mechanical oscillations of microscopic resonators have recently been observed in the quantum regime. This idea could soon be extended from localized vibrations to travelling waves thanks to a sensitive probe of so-called surface acoustic waves. |
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RPLAB @ gujma @ |
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811 |
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Hollenberg, Lloyd C. L. |
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Title |
Quantum control: Through the quantum chicane |
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Journal Article |
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2012 |
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Nature Physics |
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Nat. Phys. |
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8 |
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2 |
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113-114 |
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In quantum control there is an inherent tension between high fidelity requirements and the need for speed to avoid decoherence. A direct comparison of quantum control protocols at these two extremes indicates where the sweet spot may lie. |
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RPLAB @ gujma @ |
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812 |
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Gustafsson, Martin V.; Santos, Paulo V.; Johansson, Göran; Delsing, Per |
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Title |
Local probing of propagating acoustic waves in a gigahertz echo chamber |
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Journal Article |
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Year |
2012 |
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Nature Physics |
Abbreviated Journal |
Nat. Phys. |
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8 |
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4 |
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338-343 |
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fromIPMRAS |
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In the same way that micro-mechanical resonators resemble guitar strings and drums, surface acoustic waves resemble the sound these instruments produce, but moving over a solid surface rather than through air. In contrast with oscillations in suspended resonators, such propagating mechanical waves have not before been studied near the quantum mechanical limits. Here, we demonstrate local probing of surface acoustic waves with a displacement sensitivity of 30amRMSHz-1/2 and detection sensitivity on the single-phonon level after averaging, at a frequency of 932MHz. Our probe is a piezoelectrically coupled single-electron transistor, which is sufficiently fast, non-destructive and localized to enable us to track pulses echoing back and forth in a long acoustic cavity, self-interfering and ringing the cavity up and down. We project that strong coupling to quantum circuits will enable new experiments, and hybrids using the unique features of surface acoustic waves. Prospects include quantum investigations of phonon-phonon interactions, and acoustic coupling to superconducting qubits for which we present favourable estimates. |
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RPLAB @ gujma @ |
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813 |
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Korotkov, Alexander N. |
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Title |
Entanglement preservation: The Sleeping Beauty approach |
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Journal Article |
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Year |
2012 |
Publication |
Nature Physics |
Abbreviated Journal |
Nat. Phys. |
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Volume |
8 |
Issue |
2 |
Pages |
107-108 |
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fromIPMRAS |
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Two-qubit entanglement can be preserved by partially measuring the qubits to leave them in a 'lethargic' state. The original state is restored using quantum measurement reversal after the qubits have travelled through a decoherence channel. |
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RPLAB @ gujma @ |
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814 |
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Kim, Yong-Su; Lee, Jong-Chan; Kwon, Osung; Kim, Yoon-Ho |
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Title |
Protecting entanglement from decoherence using weak measurement and quantum measurement reversal |
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Journal Article |
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2012 |
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Nature Physics |
Abbreviated Journal |
Nat. Phys. |
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8 |
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2 |
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117-120 |
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fromIPMRAS |
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Decoherence, often caused by unavoidable coupling with the environment, leads to degradation of quantum coherence. For a multipartite quantum system, decoherence leads to degradation of entanglement and, in certain cases, entanglement sudden death. Tackling decoherence, thus, is a critical issue faced in quantum information, as entanglement is a vital resource for many quantum information applications including quantum computing, quantum cryptography, quantum teleportation and quantum metrology. Here, we propose and demonstrate a scheme to protect entanglement from decoherence. Our entanglement protection scheme makes use of the quantum measurement itself for actively battling against decoherence and it can effectively circumvent even entanglement sudden death. |
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RPLAB @ gujma @ |
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815 |
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Bason, Mark G.; Viteau, Matthieu; Malossi, Nicola; Huillery, Paul; Arimondo, Ennio; Ciampini, Donatella; Fazio, Rosario; Giovannetti, Vittorio; Mannella, Riccardo; Morsch, Oliver |
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Title |
High-fidelity quantum driving |
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Journal Article |
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2012 |
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Nature Physics |
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Nat. Phys. |
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8 |
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2 |
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147-152 |
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fromIPMRAS |
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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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RPLAB @ gujma @ |
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816 |
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Pernice, W.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G. N.; Sergienko, A. V.; Tang, H. X. |
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High speed and high efficiency travelling wave single-photon detectors embedded in nanophotonic circuits |
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Miscellaneous |
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2012 |
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arXiv |
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arXiv |
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1108.5299 |
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1-23 |
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optical waveguides, waveguide SSPD, guantum photonics, jitter, detection efficiency |
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Ultrafast, high quantum efficiency single photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. High photon detection efficiency is essential for scalable measurement-based quantum computation, quantum key distribution, and loophole-free Bell experiments. However, imperfect modal matching and finite photon absorption rates have usually limited the maximum attainable detection efficiency of single photon detectors. Here we demonstrate a superconducting nanowire detector atop nanophotonic waveguides which allows us to drastically increase the absorption length for incoming photons. When operating the detectors close to the critical current we achieve high on-chip single photon detection efficiency up to 91% at telecom wavelengths, with uncertainty dictated by the variation of the waveguide photon flux. We also observe remarkably low dark count rates without significant compromise of detection efficiency. Furthermore, our detectors are fully embedded in a scalable silicon photonic circuit and provide ultrashort timing jitter of 18ps. Exploiting this high temporal resolution we demonstrate ballistic photon transport in silicon ring resonators. The direct implementation of such a detector with high quantum efficiency, high detection speed and low jitter time on chip overcomes a major barrier in integrated quantum photonics. |
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845 |
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Shurakov, Alexander; Tong, Edward; Blundell, Raymond; Gol'tsman, Gregory |
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Title |
Microwave stabilization of HEB mixer by a microchip controller |
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2012 |
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IEEE MTT-S international microwave symposium digest |
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1-3 |
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HEB mixer stability, microwave injection, Allan variance, Allan time |
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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. |
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Montreal, QC, Canada |
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857 |
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Inderbitzin, K.; Engel, A.; Schilling, A.; Il'in, K.; Siegel, M. |
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An ultra-fast superconducting Nb nanowire single-photon detector for soft x-rays |
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2012 |
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Appl. Phys. Lett. |
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101 |
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SSPD, SNSPD, x-ray, Nb |
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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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RPLAB @ seleznev @ |
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878 |
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D. Henrich, L. Rehm S. Dörner, M. Hofherr, K. Il'in, A. Semenov, and M. Siegel |
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Detection efficiency of a spiral-nanowire superconducting single-photon detector |
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2012 |
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Critical current, Nanoscale devices, Superconducting photodetectors. |
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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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D. Henrich, L. Rehm S. Dörner, M. Hofherr, K. Il'in, A. Semenov, and M. Siegel |
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RPLAB @ seleznev @ |
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880 |
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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 |
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Superconducting single-photon counting system for optical experiments requiring time-resolution in the picosecond range |
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2012 |
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AIP REVIEW OF SCIENTIFIC INSTRUMENTS |
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83 |
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SSPD, picosecond, time-resolution |
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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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RPLAB @ seleznev @ |
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885 |
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Vercruyssen, N.; Verhagen, T. G. A.; Flokstra, M. G.; Pekola, J. P.; Klapwijk, T. M. |
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Evanescent states and nonequilibrium in driven superconducting nanowires |
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Journal Article |
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2012 |
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Phys. Rev. B |
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Phys. Rev. B |
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85 |
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224503(1-10) |
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Al HEB, Al superconducting nanowire, global state, bimodal state, quasiclassical kinetic equations, Usadel equation |
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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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Pütz, P.; Honingh, C. E.; Jacobs, K.; Justen, M.; Schultz, M.; Stutzki, J. |
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Terahertz hot electron bolometer waveguide mixers for GREAT |
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2012 |
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Astron. Astrophys. |
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A&A |
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542 |
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L2 |
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HEB mixer, applications |
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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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