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Author Pekker, David; Shah, Nayana; Sahu, Mitrabhanu; Bezryadin, Alexey; Goldbart, Paul M. doi  openurl
  Title Stochastic dynamics of phase-slip trains and superconductive-resistive switching in current-biased nanowires Type (up) Journal Article
  Year 2009 Publication Phys. Rev. B Abbreviated Journal  
  Volume 80 Issue Pages 214525 (1 to 17)  
  Keywords superconducting nanowire, phase-slip, order parameter, HEB distributed model, HEB model  
  Abstract Superconducting nanowires fabricated via carbon-nanotube templating can be used to realize and study quasi-one-dimensional superconductors. However, measurement of the linear resistance of these nanowires have been inconclusive in determining the low-temperature behavior of phase-slip fluctuations, both quantal and thermal. Thus, we are motivated to study the nonlinear current-voltage characteristics in current-biased nanowires and the stochastic dynamics of superconductive-resistive switching, as a way of probing phase-slip events. In particular, we address the question: can a single phase-slip event occurring somewhere along the wire—during which the order-parameter fluctuates to zero—induce switching, via the local heating it causes? We explore this and related issues by constructing a stochastic model for the time evolution of the temperature in a nanowire whose ends are maintained at a fixed temperature. We derive the corresponding master equation as a tool for evaluating and analyzing the mean switching time at a given value of current (smaller than the depairing critical current). The model indicates that although, in general, several phase-slip events are necessary to induce switching via a thermal runaway, there is indeed a regime of temperatures and currents in which a single event is sufficient. We carry out a detailed comparison of the results of the model with experimental measurements of the distribution of switching currents, and provide an explanation for the rather counterintuitive broadening of the distribution width that is observed upon lowering the temperature. Moreover, we identify a regime in which the experiments are probing individual phase-slip events, and thus offer a way of unearthing and exploring the physics of nanoscale quantum tunneling of the one-dimensional collective quantum field associated with the superconducting order parameter.  
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  Notes Recommended by Klapwijk Approved no  
  Call Number Serial 923  
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Author Sahu, Mitrabhanu; Bae, Myung-Ho; Rogachev, Andrey; Pekker, David; Wei, Tzu-Chieh; Shah, Nayana; Goldbart, Paul M.; Bezryadin, Alexey doi  openurl
  Title Individual topological tunnelling events of a quantum field probed through their macroscopic consequences Type (up) Journal Article
  Year 2009 Publication Nature Phys. Abbreviated Journal Nature Phys.  
  Volume 5 Issue Pages 503-508  
  Keywords phase slips, superconducting nanowires  
  Abstract Phase slips are topological fluctuations that carry the superconducting order-parameter field between distinct current-carrying states. Owing to these phase slips, superconducting nanowires acquire electrical resistance. In such wires, it is well known that at higher temperatures phase slips occur through the process of thermal barrier-crossing by the order-parameter field. At low temperatures, the general expectation is that phase slips should proceed through quantum tunnelling events, which are known as quantum phase slips. However, resistive measurements have produced evidence both for and against the occurrence of quantum phase slips. Here, we report evidence for the observation of individual quantum phase-slip events in homogeneous ultranarrow wires at high bias currents. We accomplish this through measurements of the distribution of switching currents for which the width exhibits a rather counter-intuitive, monotonic increase with decreasing temperature. Importantly, measurements show that in nanowires with larger critical currents, quantum fluctuations dominate thermal fluctuations up to higher temperatures.  
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  Notes Recommended by Klapwijk Approved no  
  Call Number Serial 928  
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Author Ovchinnikov, Yu. N.; Varlamov, A. A. url  openurl
  Title Fluctuation-dissipative phenomena in a narrow superconducting channel carrying current below critical Type (up) Journal Article
  Year 2009 Publication arXiv Abbreviated Journal  
  Volume 0910.2659v1 Issue Pages 1-4  
  Keywords superconducting nanowire, resistance calculation  
  Abstract The theory of current transport in a narrow superconducting channel accounting for thermal fluctuations is developed. These fluctuations result in the appearance of small but finite dissipation in the sample. The value of corresponding voltage is found as the function of temperature (close to transition temperature) and arbitrary bias current. It is demonstrated that the value of the activation energy (exponential factor in the Arrenius law) when current approaches to the critical one is proportional to (1-J/Jc)^(5/4). This result is in concordance with the one for the affine phenomenon of the Josephson current decay due to the thermal phase fluctuations, where the activation energy proportional (1-J/J_c)^(3/2)(the difference in the exponents is related to the additional current dependence of the order parameter). Found dependence of the activation energy on current explains the enormous discrepancy between the theoretically predicted before and the experimentally observed broadening of the resistive transition.  
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  Notes arXiv:0910.2659v1; 4 pages, 3 figures Approved no  
  Call Number Serial 931  
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Author Khosropanah P.; Baryshev A.; Zhang W.; Jellema W.; Hovenier J.N.; Gao G.R.; Klapwijk T.M; Paveliev D.G.; Williams B.S.; Kumar S.; Hu Q.; Reno J.L.; Klein B.; Hesler J.L. openurl 
  Title Phase-locking of a 2.7-THz quantum cascade laser to a microwave reference Type (up) Journal Article
  Year 2009 Publication Optics Letters Abbreviated Journal  
  Volume 34 Issue Pages 2958-2960  
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  Abstract We demonstrate the phase locking of a 2.7 THz metal–metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (X12) from a

microwave synthesizer at ~ 15 GHz. Both laser and reference radiations are coupled into a bolometer mixer, resulting in a beat signal, which is fed into a phase-lock loop. The spectral analysis of the beat signal con-firms that the QCL is phase locked. This result opens the possibility to extend heterodyne interferometers into the far-infrared range.
 
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  Call Number RPLAB @ atomics90 @ Serial 966  
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Author Marksteiner, M.; Divochiy, A.; Sclafani, M.; Haslinger, P.; Ulbricht, H.; Korneev, A.; Semenov, A.; Gol'tsman, G.; Arndt, M. url  doi
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  Title A superconducting NbN detector for neutral nanoparticles Type (up) Journal Article
  Year 2009 Publication Nanotechnol. Abbreviated Journal Nanotechnol.  
  Volume 20 Issue 45 Pages 455501  
  Keywords SSPD; SNSPD; *Electric Conductivity; Microscopy, Electron, Scanning; Nanoparticles/*chemistry/ultrastructure; Nanotechnology/*methods; *Photons  
  Abstract We present a proof-of-principle study of superconducting single photon detectors (SSPD) for the detection of individual neutral molecules/nanoparticles at low energies. The new detector is applied to characterize a laser desorption source for biomolecules and allows retrieval of the arrival time distribution of a pulsed molecular beam containing the amino acid tryptophan, the polypeptide gramicidin as well as insulin, myoglobin and hemoglobin. We discuss the experimental evidence that the detector is actually sensitive to isolated neutral particles.  
  Address University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria. markus.arndt@univie.ac.at  
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  Language English Summary Language Original Title  
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  ISSN 0957-4484 ISBN Medium  
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  Notes PMID:19822928 Approved no  
  Call Number Serial 1239  
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