56 research outputs found
Signatures of Inelastic Scattering in Coulomb-Blockade Quantum Dots
We calculate the finite-temperature conductance peak-height distributions in
Coublomb-blockade quantum dots in the limit where the inelastic scattering rate
in the dot is large compared with the mean elastic tunneling rate. The relative
reduction of the standard deviation of the peak-height distribution by a
time-reversal symmetry-breaking magnetic field, which is essentially
temperature-independent in the elastic limit, is enhanced by the inclusion of
inelastic scattering at finite temperature. We suggest this quantity as an
independent experimental probe for inelastic scattering in closed dots.Comment: 4 pages, 3 eps figures, revtex
Linear conductance in Coulomb-blockade quantum dots in the presence of interactions and spin
We discuss the calculation of the linear conductance through a
Coulomb-blockade quantum dot in the presence of interactions beyond the
charging energy. In the limit where the temperature is large compared with a
typical tunneling width, we use a rate-equations approach to describe the
transitions between the corresponding many-body states. We discuss both the
elastic and rapid-thermalization limits, where the rate of inelastic scattering
in the dot is either small or large compared with the elastic transition rate,
respectively. In the elastic limit, we find several cases where a closed
solution for the conductance is possible, including the case of a constant
exchange interaction. In the rapid-thermalization limit, a closed solution is
possible in the general case. We show that the corresponding expressions for
the linear conductance simplify for a Hamiltonian that is invariant under spin
rotations.Comment: 11 pages, no figures, revtex
The Parallel Magnetoconductance of Interacting Electrons in a Two Dimensional Disordered System
The transport properties of interacting electrons for which the spin degree
of freedom is taken into account are numerically studied for small two
dimensional diffusive clusters. On-site electron-electron interactions tend to
delocalize the electrons, while long-range interactions enhance localization.
On careful examination of the transport properties, we reach the conclusion
that it does not show a two dimensional metal insulator transition driven by
interactions. A parallel magnetic field leads to enhanced resistivity, which
saturates once the electrons become fully spin polarized. The strength of the
magnetic field for which the resistivity saturates decreases as electron
density goes down. Thus, the numerical calculations capture some of the
features seen in recent experimental measurements of parallel
magnetoconductance.Comment: 10 pages, 6 figure
Solitons in Triangular and Honeycomb Dynamical Lattices with the Cubic Nonlinearity
We study the existence and stability of localized states in the discrete
nonlinear Schr{\"o}dinger equation (DNLS) on two-dimensional non-square
lattices. The model includes both the nearest-neighbor and long-range
interactions. For the fundamental strongly localized soliton, the results
depend on the coordination number, i.e., on the particular type of the lattice.
The long-range interactions additionally destabilize the discrete soliton, or
make it more stable, if the sign of the interaction is, respectively, the same
as or opposite to the sign of the short-range interaction. We also explore more
complicated solutions, such as twisted localized modes (TLM's) and solutions
carrying multiple topological charge (vortices) that are specific to the
triangular and honeycomb lattices. In the cases when such vortices are
unstable, direct simulations demonstrate that they turn into zero-vorticity
fundamental solitons.Comment: 17 pages, 13 figures, Phys. Rev.
Exchange and the Coulomb blockade: Peak height statistics in quantum dots
We study the effect of the exchange interaction on the Coulomb blockade peak
height statistics in chaotic quantum dots. Because exchange reduces the level
repulsion in the many body spectrum, it strongly affects the fluctuations of
the peak conductance at finite temperature. We find that including exchange
substantially improves the description of the experimental data. Moreover, it
provides further evidence of the presence of high spin states (S>1) in such
systems.Comment: 5 pages, 4 figures. Published version, title change
Treatment of BXSB-Yaa Mice with IL-21R-Fc Fusion Protein Minimally Attenuates Systemic Lupus Erythematosus
A note on the ecology of the leopard {Panthera pardus Linnaeus) in the Londolozi Game Reserve, South Africa
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