11 research outputs found
Fractal Noise in Quantum Ballistic and Diffusive Lattice Systems
We demonstrate fractal noise in the quantum evolution of wave packets moving
either ballistically or diffusively in periodic and quasiperiodic tight-binding
lattices, respectively. For the ballistic case with various initial
superpositions we obtain a space-time self-affine fractal which
verify the predictions by Berry for "a particle in a box", in addition to
quantum revivals. For the diffusive case self-similar fractal evolution is also
obtained. These universal fractal features of quantum theory might be useful in
the field of quantum information, for creating efficient quantum algorithms,
and can possibly be detectable in scattering from nanostructures.Comment: 9 pages, 8 postscript figure
Quantum Supearrivals
A curious effect is uncovered by calculating the it time evolving probability
of reflection of a Gaussian wave packet from a rectangular potential barrier
while it is perturbed by reducing its height. A time interval is found during
which this probability of reflection is larger (``superarrivals'') than in the
unperturbed case. This nonclassical effect can be explained by requiring a wave
function to act as a ``field'' through which an action, induced by the
perturbation of the boundary condition, propagates at a speed depending upon
the rate of reducing the barrier height.Comment: 4 new .eps figures added. Majour changes include explanation of
superarrivals through dynamical effect induced by perturbing barrie
Decoherence of molecular wave packets in an anharmonic potential
The time evolution of anharmonic molecular wave packets is investigated under
the influence of the environment consisting of harmonic oscillators. These
oscillators represent photon or phonon modes and assumed to be in thermal
equilibrium. Our model explicitly incorporates the fact that in the case of a
nonequidistant spectrum the rates of the environment induced transitions are
different for each transition. The nonunitary time evolution is visualized by
the aid of the Wigner function related to the vibrational state of the
molecule. The time scale of decoherence is much shorter than that of
dissipation, and gives rise to states which are mixtures of localized states
along the phase space orbit of the corresponding classical particle. This
behavior is to a large extent independent of the coupling strength, the
temperature of the environment and also of the initial state.Comment: 7 pages, 4 figure
Micosi
Dopo una panoramica sul mondo dei funghi, vengono trattate le principali micosi che interessano l'alveare: ascosferosi o covata calcificata, aspergillosi o covata pietrificata e la muffa del polline (Bettsia alvei)