114 research outputs found
Interface dependence of the Josephson-current fluctuations in short SNS junctions
We discuss the dependence of the Josephson current correlations in mesoscopic
superconductor/normal-conductor/superconductor (SNS) devices on the
transparency of the superconductor/normal-conductor (SN) interfaces. Focusing
on short junctions we apply the supersymmetry method to construct an effective
field theory for mesoscopic SNS devices which is evaluated in the limit of
highly and weakly transparent interfaces. We show that the two-point
Josephson-current correlator differs by an universal factor 2 in these two
cases.Comment: 5 pages, 1figure, version accepted by PR
From clean to diffusive mesoscopic systems: A semiclassical approach to the magnetic susceptibility
We study disorder-induced spectral correlations and their effect on the
magnetic susceptibility of mesoscopic quantum systems in the non-diffusive
regime. By combining a diagrammatic perturbative approach with semiclassical
techniques we perform impurity averaging for non-translational invariant
systems. This allows us to study the crossover from clean to diffusive systems.
As an application we consider the susceptibility of non-interacting electrons
in a ballistic microstructure in the presence of weak disorder. We present
numerical results for a square billiard and approximate analytic results for
generic chaotic geometries. We show that for the elastic mean free path
larger than the system size, there are two distinct regimes of behaviour
depending on the relative magnitudes of and an inelastic scattering
length.Comment: 7 pages, Latex-type, EuroMacr, 4 Postscript figures, to appear in
Europhys. Lett. 199
Bosonization for disordered and chaotic systems
Using a supersymmetry formalism, we reduce exactly the problem of electron
motion in an external potential to a new supermatrix model valid at all
distances. All approximate nonlinear sigma models obtained previously for
disordered systems can be derived from our exact model using a coarse-graining
procedure. As an example, we consider a model for a smooth disorder and
demonstrate that using our approach does not lead to a 'mode-locking' problem.
As a new application, we consider scattering on strong impurities for which the
Born approximation cannot be used. Our method provides a new calculational
scheme for disordered and chaotic systems.Comment: 4 pages, no figure, REVTeX4; title changed, revision for publicatio
The effect of Fermi surface curvature on low-energy properties of fermions with singular interactions
We discuss the effect of Fermi surface curvature on long-distance/time
asymptotic behaviors of two-dimensional fermions interacting via a gapless mode
described by an effective gauge field-like propagator. By comparing the
predictions based on the idea of multi-dimensional bosonization with those of
the strong- coupling Eliashberg approach, we demonstrate that an agreement
between the two requires a further extension of the former technique.Comment: Latex, 4+ pages. Phys. Rev. Lett., to appea
Role of divergence of classical trajectories in quantum chaos
We study logarithmical in effects in the statistical description of
quantum chaos. We found analytical expressions for the deviations from the
universality in the weak localization corrections and the level statistics and
showed that the characteristic scale for these deviations is the Ehrenfest
time, , where is the Lyapunov exponent
of the classical motion.Comment: 4 pages, no figure
Nonequilibrium kinetics of a disordered Luttinger liquid
We develop a kinetic theory for strongly correlated disordered
one-dimensional electron systems out of equilibrium, within the Luttinger
liquid model. In the absence of inhomogeneities, the model exhibits no
relaxation to equilibrium. We derive kinetic equations for electron and plasmon
distribution functions in the presence of impurities and calculate the
equilibration rate . Remarkably, for not too low temperature and bias
voltage, is given by the elastic backscattering rate, independent of
the strength of electron-electron interaction, temperature, and bias.Comment: 4 pages, 3 figures, revised versio
Field Theory of Mesoscopic Fluctuations in Superconductor/Normal-Metal Systems
Thermodynamic and transport properties of normal disordered conductors are
strongly influenced by the proximity of a superconductor. A cooperation between
mesoscopic coherence and Andreev scattering of particles from the
superconductor generates new types of interference phenomena. We introduce a
field theoretic approach capable of exploring both averaged properties and
mesoscopic fluctuations of superconductor/normal-metal systems.
As an example the method is applied to the study of the level statistics of a
SNS-junction.Comment: 4 pages, REVTEX, two eps-figures included; submitted to JETP letter
Statistics of Rare Events in Disordered Conductors
Asymptotic behavior of distribution functions of local quantities in
disordered conductors is studied in the weak disorder limit by means of an
optimal fluctuation method. It is argued that this method is more appropriate
for the study of seldom occurring events than the approaches based on nonlinear
-models because it is capable of correctly handling fluctuations of the
random potential with large amplitude as well as the short-scale structure of
the corresponding solutions of the Schr\"{o}dinger equation. For two- and
three-dimensional conductors new asymptotics of the distribution functions are
obtained which in some cases differ significantly from previously established
results.Comment: 17 pages, REVTeX 3.0 and 1 Postscript figur
A minimal approach for the local statistical properties of a one-dimensional disordered wire
We consider a one-dimensional wire in gaussian random potential. By treating
the spatial direction as imaginary time, we construct a `minimal'
zero-dimensional quantum system such that the local statistical properties of
the wire are given as products of statistically independent matrix elements of
the evolution operator of the system. The space of states of this quantum
system is found to be a particular non-unitary, infinite dimensional
representation of the pseudo-unitary group, U(1,1). We show that our
construction is minimal in a well defined sense, and compare it to the
supersymmetry and Berezinskii techniques.Comment: 10 pages, 0 figure
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