282 research outputs found
Recycling of the yeast v-SNARE Sec22p involves COPI-proteins and the ER transmembrane proteins Ufe1p and Sec20p.
Localization-delocalization transition in the quasi-one-dimensional ladder chain with correlated disorder
The generalization of the dimer model on a two-leg ladder is defined and
investigated both, analytically and numerically. For the closed system we
calculate the Landauer resistance analytically and found the presence of the
point of delocalization at the band center which is confirmed by the numerical
calculations of the Lyapunov exponent. We calculate also analytically the
localization length index and present the numerical investigations of the
density of states (DOS). For the open counterpart of this model the
distribution of the Wigner delay times is calculated numerically. It is shown
how the localization-delocalization transition manifest itself in the behavior
of the distribution.Comment: 9 pages, 10 figures, Revte
A super-Ohmic energy absorption in driven quantum chaotic systems
We consider energy absorption by driven chaotic systems of the symplectic
symmetry class. According to our analytical perturbative calculation, at the
initial stage of evolution the energy growth with time can be faster than
linear. This appears to be an analog of weak anti-localization in disordered
systems with spin-orbit interaction. Our analytical result is also confirmed by
numerical calculations for the symplectic quantum kicked rotor.Comment: 4 pages, 2 figure
Sec12p requires Rer1p for sorting to coatomer (COPI)-coated vesicles and retrieval to the ER
Statistics of resonances and of delay times in quasiperiodic Schr"odinger equations
We study the statistical distributions of the resonance widths , and of delay times in one dimensional
quasi-periodic tight-binding systems with one open channel. Both quantities are
found to decay algebraically as , and on
small and large scales respectively. The exponents , and are
related to the fractal dimension of the spectrum of the closed system
as and . Our results are verified for the
Harper model at the metal-insulator transition and for Fibonacci lattices.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
Distribution of the local density of states, reflection coefficient and Wigner delay time in absorbing ergodic systems at the point of chiral symmetry
Employing the chiral Unitary Ensemble of random matrices we calculate the
probability distribution of the local density of states for zero-dimensional
("quantum chaotic") two-sublattice systems at the point of chiral symmetry E=0
and in the presence of uniform absorption. The obtained result can be used to
find the distributions of the reflection coefficent and of the Wigner time
delay for such systems.Comment: 4 pages, 3 figure
Anderson localization transition with long-ranged hoppings : analysis of the strong multifractality regime in terms of weighted Levy sums
For Anderson tight-binding models in dimension with random on-site
energies and critical long-ranged hoppings decaying
typically as , we show that the strong multifractality
regime corresponding to small can be studied via the standard perturbation
theory for eigenvectors in quantum mechanics. The Inverse Participation Ratios
, which are the order parameters of Anderson transitions, can be
written in terms of weighted L\'evy sums of broadly distributed variables (as a
consequence of the presence of on-site random energies in the denominators of
the perturbation theory). We compute at leading order the typical and
disorder-averaged multifractal spectra and as a
function of . For , we obtain the non-vanishing limiting spectrum
as . For , this method
yields the same disorder-averaged spectrum of order as
obtained previously via the Levitov renormalization method by Mirlin and Evers
[Phys. Rev. B 62, 7920 (2000)]. In addition, it allows to compute explicitly
the typical spectrum, also of order , but with a different -dependence
for all . As a consequence, we find
that the corresponding singularity spectra and
differ even in the positive region , and vanish at
different values , in contrast to the standard
picture. We also obtain that the saddle value of the Legendre
transform reaches the termination point where
only in the limit .Comment: 13 pages, 2 figures, v2=final versio
Statistical properties of phases and delay times of the one-dimensional Anderson model with one open channel
We study the distribution of phases and of Wigner delay times for a
one-dimensional Anderson model with one open channel. Our approach, based on
classical Hamiltonian maps, allows us an analytical treatment. We find that the
distribution of phases depends drastically on the parameter where is the variance of the disorder distribution and
the wavevector. It undergoes a transition from uniformity to singular
behaviour as increases. The distribution of delay times shows
universal power law tails , while the short time behaviour is
- dependent.Comment: 4 pages, 2 figures, Submitted to PR
Quantum mechanical relaxation of open quasiperiodic systems
We study the time evolution of the survival probability in open
one-dimensional quasiperiodic tight-binding samples of size , at critical
conditions. We show that it decays algebraically as up
to times , where , and
is the fractal dimension of the spectrum of the closed system. We
verified these results for the Harper model at the metal-insulator transition
and for Fibonacci lattices. Our predictions should be observable in propagation
experiments with electrons or classical waves in quasiperiodic superlattices or
dielectric multilayers.Comment: 4 pages, 5 figure
Semiclassical Construction of Random Wave Functions for Confined Systems
We develop a statistical description of chaotic wavefunctions in closed
systems obeying arbitrary boundary conditions by combining a semiclassical
expression for the spatial two-point correlation function with a treatment of
eigenfunctions as Gaussian random fields. Thereby we generalize Berry's
isotropic random wave model by incorporating confinement effects through
classical paths reflected at the boundaries. Our approach allows to explicitly
calculate highly non-trivial statistics, such as intensity distributions, in
terms of usually few short orbits, depending on the energy window considered.
We compare with numerical quantum results for the Africa billiard and derive
non-isotropic random wave models for other prominent confinement geometries.Comment: To be submitted to Physical Review Letter
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