13,046 research outputs found
Scattering Theory for Quantum Hall Anyons in a Saddle Point Potential
We study the theory of scattering of two anyons in the presence of a
quadratic saddle-point potential and a perpendicular magnetic field. The
scattering problem decouples in the centre-of-mass and the relative
coordinates. The scattering theory for the relative coordinate encodes the
effects of anyon statistics in the two-particle scattering. This is fully
characterized by two energy-dependent scattering phase shifts. We develop a
method to solve this scattering problem numerically, using a generalized lowest
Landau level approximation.Comment: 5 pages. Published version, with clarified presentatio
Spectroscopic properties of large open quantum-chaotic cavities with and without separated time scales
The spectroscopic properties of an open large Bunimovich cavity are studied
numerically in the framework of the effective Hamiltonian formalism. The cavity
is opened by attaching leads to it in four different ways. In some cases,
short-lived and long-lived resonance states coexist. The short-lived states
cause traveling waves in the transmission while the long-lived ones generate
superposed fluctuations. The traveling waves oscillate as a function of energy.
They are not localized in the interior of the large chaotic cavity. In other
cases, the transmission takes place via standing waves with an intensity that
closely follows the profile of the resonances. In all considered cases, the
phase rigidity fluctuates with energy. It is mostly near to its maximum value
and agrees well with the theoretical value for the two-channel case. As shown
in the foregoing paper \cite{1}, all cases are described well by the Poisson
kernel when the calculation is restricted to an energy region in which the
average matrix is (nearly) constant.Comment: 13 pages, 4 figure
Effect of gas flow on electronic transport in a DNA-decorated carbon nanotube
We calculate the two-time current correlation function using the experimental
data of the current-time characteristics of the Gas-DNA-decorated carbon
nanotube field effect transistor. The pattern of the correlation function is a
measure of the sensitivity and selectivity of the sensors and suggest that
these gas flow sensors may also be used as DNA sequence detectors. The system
is modelled by a one-dimensional tight-binding Hamiltonian and we present
analytical calculations of quantum electronic transport for the system using
the time-dependent nonequilibrium Green's function formalism and the adiabatic
expansion. The zeroth and first order contributions to the current
and are calculated, where is the Landauer formula. The formula for the time-dependent current
is then used to compare the theoretical results with the experiment.Comment: 14 pages, 5 figures and 2 table
Correlated behavior of conductance and phase rigidity in the transition from the weak-coupling to the strong-coupling regime
We study the transmission through different small systems as a function of
the coupling strength to the two attached leads. The leads are identical
with only one propagating mode in each of them. Besides the
conductance , we calculate the phase rigidity of the scattering wave
function in the interior of the system. Most interesting results are
obtained in the regime of strongly overlapping resonance states where the
crossover from staying to traveling modes takes place. The crossover is
characterized by collective effects. Here, the conductance is plateau-like
enhanced in some energy regions of finite length while corridors with zero
transmission (total reflection) appear in other energy regions. This
transmission picture depends only weakly on the spectrum of the closed system.
It is caused by the alignment of some resonance states of the system with the
propagating modes in the leads. The alignment of resonance states
takes place stepwise by resonance trapping, i.e. it is accompanied by the
decoupling of other resonance states from the continuum of propagating modes.
This process is quantitatively described by the phase rigidity of the
scattering wave function. Averaged over energy in the considered energy window,
is correlated with . In the regime of strong coupling, only two
short-lived resonance states survive each aligned with one of the channel wave
functions . They may be identified with traveling modes through the
system. The remaining trapped narrow resonance states are well separated
from one another.Comment: Resonance trapping mechanism explained in the captions of Figs. 7 to
11. Recent papers added in the list of reference
Quantum transport through molecular wires
We explore electron transport properties in molecular wires made of
heterocyclic molecules (pyrrole, furan and thiophene) by using the Green's
function technique. Parametric calculations are given based on the
tight-binding model to describe the electron transport in these wires. It is
observed that the transport properties are significantly influenced by (a) the
heteroatoms in the heterocyclic molecules and (b) the molecule-to-electrodes
coupling strength. Conductance () shows sharp resonance peaks associated
with the molecular energy levels in the limit of weak molecular coupling, while
they get broadened in the strong molecular coupling limit. These resonances get
shifted with the change of the heteroatoms in these heterocyclic molecules. All
the essential features of the electron transfer through these molecular wires
become much more clearly visible from the study of our current-voltage
(-) characteristics, and they provide several key informations in the
study of molecular transport.Comment: 8 pages, 4 figure
Effect of hydrogen adsorption on the quasiparticle spectra of graphene
We use the non-interacting tight-binding model to study the effect of
isolated hydrogen adsorbates on the quasiparticle spectra of single-layer
graphene. Using the Green's function approach, we obtain analytic expressions
for the local density of states and the spectral function of hydrogen-doped
graphene, which are also numerically evaluated and plotted. Our results are
relevant for the interpretation of scanning tunneling microscopy and
angle-resolved photoemission spectroscopy data of functionalized graphene.Comment: 4 pages, 3 figures, minor corrections to tex
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Convergence Rates for Quantum Evolution and Entropic Continuity Bounds in Infinite Dimensions
By extending the concept of energy-constrained diamond norms, we obtain
continuity bounds on the dynamics of both closed and open quantum systems in
infinite-dimensions, which are stronger than previously known bounds. We
extensively discuss applications of our theory to quantum speed limits,
attenuator and amplifier channels, the quantum Boltzmann equation, and quantum
Brownian motion. Next, we obtain explicit log-Lipschitz continuity bounds for
entropies of infinite-dimensional quantum systems, and classical capacities of
infinite-dimensional quantum channels under energy-constraints. These bounds
are determined by the high energy spectrum of the underlying Hamiltonian and
can be evaluated using Weyl's law
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