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Beck M, Rousseau I, Klammer M, Leiderer P, Mittendorff M, Winnerl S, et al. Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses. Phys Rev Lett. 2013;110(26):267003 (1 to 5).
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.
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Novotny L. Effective wavelength scaling for optical antennas. Phys Rev Lett. 2007;98(26):266802(1–4).
Abstract: In antenna theory, antenna parameters are directly related to the wavelength λ of incident radiation, but this scaling fails at optical frequencies where metals behave as strongly coupled plasmas. In this Letter we show that antenna designs can be transferred to the optical frequency regime by replacing λ by a linearly scaled effective wavelength λeff=n1+n2λ/λp, with λp being the plasma wavelength and n1, n2 being coefficients that depend on geometry and material properties. It is assumed that the antenna is made of linear segments with radii Râ‰<aa>λ. Optical antennas hold great promise for increasing the efficiency of photovoltaics, light-emitting devices, and optical sensors.
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Shah N, Pekker D, Goldbart PM. Inherent stochasticity of superconductor-resistor switching behavior in nanowires. Phys Rev Lett. 2008;101:207001(1 to 4).
Abstract: We study the stochastic dynamics of superconductive-resistive switching in hysteretic current-biased superconducting nanowires undergoing phase-slip fluctuations. We evaluate the mean switching time using the master-equation formalism, and hence obtain the distribution of switching currents. We find that as the temperature is reduced this distribution initially broadens; only at lower temperatures does it show the narrowing with cooling naively expected for phase slips that are thermally activated. We also find that although several phase-slip events are generally necessary to induce switching, there is an experimentally accessible regime of temperatures and currents for which just one single phase-slip event is sufficient to induce switching, via the local heating it causes.
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Anthore A, Pothier H, Esteve D. Density of states in a superconductor carrying a supercurrent. Phys Rev Lett. 2003;90(12):127001 (1 to 4).
Abstract: We have measured the tunneling density of states (DOS) in a superconductor carrying a supercurrent or exposed to an external magnetic field. The pair correlations are weakened by the supercurrent, leading to a modification of the DOS and to a reduction of the gap. As predicted by the theory of superconductivity in diffusive metals, we find that this effect is similar to that of an external magnetic field.
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Pothier H, Guéron S, Birge NO, Esteve D, Devoret MH. Energy distribution function of quasiparticles in mesoscopic wires. Phys. Rev. Lett.. 1997;79(18):3490–3.
Abstract: We have measured with a tunnel probe the energy distribution function of Landau quasiparticles in metallic diffusive wires connected to two reservoir electrodes, with an applied bias voltage. The distribution function in the middle of a 1.5-μm-long wire resembles the half sum of the Fermi distributions of the reservoirs. The distribution functions in 5-μm-long wires are more rounded, due to interactions between quasiparticles during the longer diffusion time across the wire. From the scaling of the data with the bias voltage, we find that the scattering rate between two quasiparticles varies as <c9><203a>–2, where <c9><203a> is the energy transferred.
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Shah J, Pinczuk A, Gossard AC, Wiegmann W. Energy-loss rates for hot electrons and holes in GaAs quantum wells. Phys Rev Lett. 1985;54:2045–8.
Abstract: We report the first direct determination of carrier-energy-loss rates in a semiconductor. These measurements provide fundamental insight into carrier-phonon interactions in semiconductors. Unexpectedly large differences are found in the energy-loss rates for electrons and holes in GaAs/AlGaAs quantum wells. This large difference results from an anomalously low electron-energy-loss rate, which we attribute to the presence of nonequilibrium optical phonons rather than the effects of reduced dimensionality or dynamic screening.
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Johnson MA, Betz AL, Townes CH. 10-μm Heterodyne Stellar Interferometer. Phys. Rev. Lett.. 1974;33(27):1617–20.
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Usadel KD. Generalized diffusion equation for superconducting alloys. Phys Rev Lett. 1970;25(8):507.
Abstract: Eilenberger's transportlike equations for a superconductor of type II can be simplified very much in the dirty limit. In this limit a diffusionlike equation is derived which is the generalization of the de Gennes-Maki theory for dirty superconductors to arbitrary values of the order parameter.
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