7 research outputs found
Full Counting Statistics of Multiple Andreev Reflections in incoherent diffusive superconducting junctions
We present a theory for the full distribution of current fluctuations in
incoherent diffusive superconducting junctions, subjected to a voltage bias.
This theory of full counting statistics of incoherent multiple Andreev
reflections is valid for arbitrary applied voltage. We present a detailed
discussion of the properties of the first four cumulants as well as the low and
high voltage regimes of the full counting statistics. The work is an extension
of the results of Pilgram and the author, Phys. Rev. Lett. 94, 086806 (2005).Comment: Included in special issue Spin Physics of Superconducting
heterostructures of Applied Physics A: Materials Science & Processin
Proximity Effect and Multiple Andreev Reflections in Chaotic Josephson junctions
We study the dc-current transport in a voltage biased superconductor-chaotic
dot-superconductor junction with an induced proximity effect(PE) in the dot. It
is found that for a Thouless energy of the dot smaller than the
superconducting energy gap , the PE is manifested as peaks in the
differential conductance at voltages of order away from the even
subharmonic gap structures . These peaks are
insensitive to temperatures but are suppressed by a weak
magnetic field. The current for suppressed PE is independent of and
magnetic field and is shown to be given by the Octavio-Tinkham-Blonder-Klapwijk
theory.Comment: 4 pages, 3 figure
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.
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 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