Mesoscopic fluctuations in the shot-noise power of metals

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Shot noise in mesoscopic systems

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Andreev reflection in ferromagnet-superconductor junctions

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Semiclassical theory of shot noise in mesoscopic conductors

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Samenwerkingsvormen boer & burger

De agrarische sector is volop in beweging om de verbinding met de stad en de burger te maken. Een mogelijk motief hiervoor is transparantie. Het gaat hier vooral om vrijblijvend contact en eenrichtingsverkeer (boer richtingburger). In deze studie wordt geprobeerd te achterhalen hoe dat komt en wat er aan gedaan moet worden om meer initiatieven op het gebied van samenwerking van de grond te krijgen. De studie is als volgt uitgevoerd: een korte verkenning van binnenlandse en buitenlandse literatuur, interviews met stakeholders en een workshop met alle betrokkenen

Calculation of nanowire thermal conductivity using complete phonon dispersion relations

The lattice thermal conductivity of crystalline Si nanowires is calculated. The calculation uses complete phonon dispersions, and does not require any externally imposed frequency cutoffs. No adjustment to nanowire thermal conductivity measurements is required. Good agreement with experimental results for nanowires wider than 35 nm is obtained. A formulation in terms of the transmission function is given. Also, the use of a simpler, nondispersive "Callaway formula", is discussed from the complete dispersions perspective.Comment: 4 pages, 3 figures. Accepted in Phys. Rev.

Current noise in long diffusive SNS junctions in the incoherent MAR regime

Spectral density of current fluctuations at zero frequency is calculated for a long diffusive SNS junction with low-resistive interfaces. At low temperature, T << Delta, the subgap shot noise approaches linear voltage dependence, S=(2/ 3R)(eV + 2Delta), which is the sum of the shot noise of the normal conductor and voltage independent excess noise. This result can also be interpreted as the 1/3-suppressed Poisson noise for the effective charge q = e(1+2Delta/eV) transferred by incoherent multiple Andreev reflections (MAR). At higher temperatures, anomalies of the current noise develop at the gap subharmonics, eV = 2Delta/n. The crossover to the hot electron regime from the MAR regime is analyzed in the limit of small applied voltages.Comment: improved version, to be published in Phys. Rev.

Shot noise of series quantum point contacts intercalating chaotic cavities

Shot noise of series quantum point contacts forming a sequence of cavities in a two dimensional electron gas are studied theoretically and experimentally. Noise in such a structure originates from local scattering at the point contacts as well as from chaotic motion of the electrons in the cavities. We found that the measured shot noise is in reasonable agreement with our theoretical prediction taking the cavity noise into account.Comment: 4 pages, 5 figure

Nonlocal effects in the shot noise of diffusive superconductor - normal-metal systems

A cross-shaped diffusive system with two superconducting and two normal electrodes is considered. A voltage $eV < \Delta$ is applied between the normal leads. Even in the absence of average current through the superconducting electrodes their presence increases the shot noise at the normal electrodes and doubles it in the case of a strong coupling to the superconductors. The nonequilibrium noise at the superconducting electrodes remains finite even in the case of a vanishingly small transport current due to the absence of energy transfer into the superconductors. This noise is suppressed by electron-electron scattering at sufficiently high voltages.Comment: 4 pages, RevTeX, 2 eps figure