195 research outputs found
High-Velocity Estimates and Inverse Scattering for Quantum N-Body Systems with Stark Effect
In an N-body quantum system with a constant electric field, by inverse
scattering, we uniquely reconstruct pair potentials, belonging to the optimal
class of short-range potentials and long-range potentials, from the
high-velocity limit of the Dollard scattering operator. We give a
reconstruction formula with an error term.Comment: In this published version we have added remarks and we have edited
the pape
Kondo physics in transport through a quantum dot with Luttinger liquid leads
We study the gate voltage dependence of the linear conductance through a
quantum dot coupled to one-dimensional leads. For interacting dot electrons but
noninteracting leads Kondo physics implies broad plateau-like resonances. In
the opposite case Luttinger liquid behavior leads to sharp resonances. In the
presence of Kondo as well as Luttinger liquid physics and for experimentally
relevant parameters, we find a line shape that resembles the one of the Kondo
case.Comment: 4+ pages, 4 figures include
Bounds on Total Cross Sections in Atom-Atom and Atom-Ion Collisions by Geometric Methods
A method is presented for obtaining explicit bounds for the total cross section (including scattering into several final charged fragments) for the scattering of two bound clusters of nuclei and electrons so long as either both clusters are neutral or one is neutral and without an electric dipole moment
Філософсько-аналітичний погляд на категорію заробітної плати в контексті побудови облікового процесу установ бюджетної та фінансово-кредитної сфери
Optical conductivity near finite-wavelength quantum criticality
We study the optical conductivity sigma(Omega) of an electron system near a
quantum-critical point with finite-wavelength ordering. sigma(Omega) vanishes
in clean Galilean-invariant systems, unless electrons are coupled to dynamical
collective modes, which dissipate the current. This coupling introduces a
nonuniversal energy scale. Depending on the parameters of each specific system,
a variety of responses arise near criticality: scaling peaks at a temperature-
and doping-dependent frequency, peaks at a fixed frequency, or no peaks to be
associated with criticality. Therefore the lack of scaling in the far-infrared
conductivity in cuprates does not necessarily call for new concepts of quantum
criticality.Comment: 4 pages, 4 figures; version as publishe
Renormalization-group analysis of the one-dimensional extended Hubbard model with a single impurity
We analyze the one-dimensional extended Hubbard model with a single static
impurity by using a computational technique based on the functional
renormalization group. This extends previous work for spinless fermions to
spin-1/2 fermions. The underlying approximations are devised for weak
interactions and arbitrary impurity strengths, and have been checked by
comparing with density-matrix renormalization-group data. We present results
for the density of states, the density profile and the linear conductance.
Two-particle backscattering leads to striking effects, which are not captured
if the bulk system is approximated by its low-energy fixed point, the Luttinger
model. In particular, the expected decrease of spectral weight near the
impurity and of the conductance at low energy scales is often preceded by a
pronounced increase, and the asymptotic power laws are modified by logarithmic
corrections.Comment: 36 pages, 13 figures, revised version as publishe
Strain sensing with sub-micron sized Al-AlOx-Al tunnel junctions
We demonstrate a local strain sensing method for nanostructures based on
metallic Al tunnel junctions with AlOx barriers. The junctions were fabricated
on top of a thin silicon nitride membrane, which was actuated with an AFM tip
attached to a stiff cantilever. A large relative change in the tunneling
resistance in response to the applied strain (gauge factor) was observed, up to
a value 37. This facilitates local static strain variation measurements down to
~10^{-7}.Comment: 4 pages, 3 figure
Bounds on Total Cross Sections in Atom-Atom and Atom-Ion Collisions by Geometric Methods
A method is presented for obtaining explicit bounds for the total cross section (including scattering into several final charged fragments) for the scattering of two bound clusters of nuclei and electrons so long as either both clusters are neutral or one is neutral and without an electric dipole moment
Fermionic renormalization group methods for transport through inhomogeneous Luttinger liquids
We compare two fermionic renormalization group methods which have been used
to investigate the electronic transport properties of one-dimensional metals
with two-particle interaction (Luttinger liquids) and local inhomogeneities.
The first one is a poor man's method setup to resum ``leading-log'' divergences
of the effective transmission at the Fermi momentum. Generically the resulting
equations can be solved analytically. The second approach is based on the
functional renormalization group method and leads to a set of differential
equations which can only for certain setups and in limiting cases be solved
analytically, while in general it must be integrated numerically. Both methods
are claimed to be applicable for inhomogeneities of arbitrary strength and to
capture effects of the two-particle interaction, such as interaction dependent
exponents, up to leading order. We critically review this for the simplest case
of a single impurity. While on first glance the poor man's approach seems to
describe the crossover from the ``perfect'' to the ``open chain fixed point''
we collect evidence that difficulties may arise close to the ``perfect chain
fixed point''. Due to a subtle relation between the scaling dimensions of the
two fixed points this becomes apparent only in a detailed analysis. In the
functional renormalization group method the coupling of the different
scattering channels is kept which leads to a better description of the
underlying physics.Comment: 25 pages, accepted for publication in NJP, remarks added on the poor
man's RG treatment of the Y-junction and the Breit-Wigner line shape
Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter
The Thorium-229 isotope features a nuclear isomer state with an extremely low
energy. The currently most accepted energy value, 7.8 +- 0.5 eV, was obtained
from an indirect measurement using a NASA x-ray microcalorimeter with an
instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic
microcalorimeters with an energy resolution down to a few eV can be used to
measure the isomer energy. In particular, resolving the 29.18 keV doublet in
the \gamma-spectrum following the \alpha-decay of Uranium-233, corresponding to
the decay into the ground and isomer state, allows to measure the isomer
transition energy without additional theoretical input parameters, and increase
the energy accuracy. We study the possibility of resolving the 29.18 keV line
as a doublet and the dependence of the attainable precision of the energy
measurement on the signal and background count rates and the instrumental
resolution.Comment: 32 pages, 8 figures, eq. (3) correcte
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