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Author Yang, Y.; Fedorov, G.; Shafranjuk, S. E.; Klapwijk, T. M.; Cooper, B. K.; Lewis, R. M.; Lobb, C. J.; Barbara, P.
Title Electronic transport and possible superconductivity at Van Hove singularities in carbon nanotubes Type Journal Article
Year 2015 Publication Nano Lett. Abbreviated Journal Nano Lett.
Volume 15 Issue 12 Pages 7859-7866
Keywords carbon nanotubes, CNT, tunable superconductivity, van Hove singularities
Abstract Van Hove singularities (VHSs) are a hallmark of reduced dimensionality, leading to a divergent density of states in one and two dimensions and predictions of new electronic properties when the Fermi energy is close to these divergences. In carbon nanotubes, VHSs mark the onset of new subbands. They are elusive in standard electronic transport characterization measurements because they do not typically appear as notable features and therefore their effect on the nanotube conductance is largely unexplored. Here we report conductance measurements of carbon nanotubes where VHSs are clearly revealed by interference patterns of the electronic wave functions, showing both a sharp increase of quantum capacitance, and a sharp reduction of energy level spacing, consistent with an upsurge of density of states. At VHSs, we also measure an anomalous increase of conductance below a temperature of about 30 K. We argue that this transport feature is consistent with the formation of Cooper pairs in the nanotube.
Address (down) Department of Physics, Georgetown University , Washington, District of Columbia 20057, United States
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ISSN 1530-6984 ISBN Medium
Area Expedition Conference
Notes PMID:26506109; Suuplementary info (attached to pdf) DOI: 10.1021/acs.nanolett.5b02564 Approved no
Call Number Serial 1782
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Author Beck, M.; Rousseau, I.; Klammer, M.; Leiderer, P.; Mittendorff, M.; Winnerl, S.; Helm, M.; Gol'tsman, G.N.; Demsar, J.
Title Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses Type Journal Article
Year 2013 Publication Phys. Rev. Lett. Abbreviated Journal Phys. Rev. Lett.
Volume 110 Issue 26 Pages 267003 (1 to 5)
Keywords NbN thin films, energy gap
Abstract Observations of radiation-enhanced superconductivity have thus far been limited to a few type-I superconductors (Al, Sn) excited at frequencies between the inelastic scattering rate and the superconducting gap frequency 2Delta/h. Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above 2Delta/h of a BCS superconductor NbN, we demonstrate that the superconducting gap can be transiently increased also in a type-II dirty-limit superconductor. The effect is particularly pronounced at higher temperatures and is attributed to radiation induced nonthermal electron distribution persisting on a 100 ps time scale.
Address (down) Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457, Germany
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ISSN 0031-9007 ISBN Medium
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Notes PMID:23848912 Approved no
Call Number Serial 1370
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Author Pyatkov, F.; Khasminskaya, S.; Kovalyuk, V.; Hennrich, F.; Kappes, M. M.; Goltsman, G. N.; Pernice, W. H. P.; Krupke, R.
Title Sub-nanosecond light-pulse generation with waveguide-coupled carbon nanotube transducers Type Journal Article
Year 2017 Publication Beilstein J. Nanotechnol. Abbreviated Journal Beilstein J. Nanotechnol.
Volume 8 Issue Pages 38-44
Keywords carbon nanotubes; CNT; infrared; integrated optics devices; nanomaterials
Abstract Carbon nanotubes (CNTs) have recently been integrated into optical waveguides and operated as electrically-driven light emitters under constant electrical bias. Such devices are of interest for the conversion of fast electrical signals into optical ones within a nanophotonic circuit. Here, we demonstrate that waveguide-integrated single-walled CNTs are promising high-speed transducers for light-pulse generation in the gigahertz range. Using a scalable fabrication approach we realize hybrid CNT-based nanophotonic devices, which generate optical pulse trains in the range from 200 kHz to 2 GHz with decay times below 80 ps. Our results illustrate the potential of CNTs for hybrid optoelectronic systems and nanoscale on-chip light sources.
Address (down) Department of Materials and Earth Sciences, Technische Universitat Darmstadt, Darmstadt 64287, Germany
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ISSN 2190-4286 ISBN Medium
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Notes PMID:28144563; PMCID:PMC5238692 Approved no
Call Number RPLAB @ kovalyuk @ Serial 1109
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Author Pernice, W. H. P.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G. N.; Sergienko, A. V.; Tang, H. X.
Title High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits Type Journal Article
Year 2012 Publication Nat. Commun. Abbreviated Journal Nat. Commun.
Volume 3 Issue Pages 1325 (1 to 10)
Keywords waveguide SSPD
Abstract Ultrafast, high-efficiency single-photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. However, imperfect modal matching and finite photon absorption rates have usually limited their maximum attainable detection efficiency. Here we demonstrate superconducting nanowire detectors atop nanophotonic waveguides, which enable a drastic increase of the absorption length for incoming photons. This allows us to achieve high on-chip single-photon detection efficiency up to 91% at telecom wavelengths, repeatable across several fabricated chips. We also observe remarkably low dark count rates without significant compromise of the on-chip detection efficiency. The detectors are fully embedded in scalable silicon photonic circuits and provide ultrashort timing jitter of 18 ps. Exploiting this high temporal resolution, we demonstrate ballistic photon transport in silicon ring resonators. Our direct implementation of a high-performance single-photon detector on chip overcomes a major barrier in integrated quantum photonics.
Address (down) Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, USA
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ISSN 2041-1723 ISBN Medium
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Notes PMID:23271658; PMCID:PMC3535416 Approved no
Call Number Serial 1375
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Author Mohan, N.; Minaeva, O.; Gol'tsman, G. N.; Nasr, M. B.; Saleh, B. E.; Sergienko, A. V.; Teich, M. C.
Title Photon-counting optical coherence-domain reflectometry using superconducting single-photon detectors Type Journal Article
Year 2008 Publication Opt. Express Abbreviated Journal Opt. Express
Volume 16 Issue 22 Pages 18118-18130
Keywords SSPD, SNSPD
Abstract We consider the use of single-photon counting detectors in coherence-domain imaging. Detectors operated in this mode exhibit reduced noise, which leads to increased sensitivity for weak light sources and weakly reflecting samples. In particular, we experimentally demonstrate the possibility of using superconducting single-photon detectors (SSPDs) for optical coherence-domain reflectometry (OCDR). These detectors are sensitive over the full spectral range that is useful for carrying out such imaging in biological samples. With counting rates as high as 100 MHz, SSPDs also offer a high rate of data acquisition if the light flux is sufficient.
Address (down) Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA. nm82@bu.edu
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Series Volume Series Issue Edition
ISSN 1094-4087 ISBN Medium
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Notes PMID:18958090 Approved no
Call Number Serial 1407
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