61 research outputs found
Ground state energies of quantum dots in high magnetic fields: A new approach
We present a new method for calculating ground state properties of quantum
dots in high magnetic fields. It takes into account the equilibrium positions
of electrons in a Wigner cluster to minimize the interaction energy in the high
field limit. Assuming perfect spin alignment the many-body trial function is a
single Slater determinant of overlapping oscillator functions from the lowest
Landau level centered at and near the classical equilibrium positions. We
obtain an analytic expression for the ground state energy and present numerical
results for up to N=40.Comment: 4 pages, including 2 figures, contribution to the Proceedings of
EP2DS-14, submitted to Physica
Ground state energies of quantum dots in high magnetic fields: A new approach
We present a new method for calculating ground state properties of quantum
dots in high magnetic fields. It takes into account the equilibrium positions
of electrons in a Wigner cluster to minimize the interaction energy in the high
field limit. Assuming perfect spin alignment the many-body trial function is a
single Slater determinant of overlapping oscillator functions from the lowest
Landau level centered at and near the classical equilibrium positions. We
obtain an analytic expression for the ground state energy and present numerical
results for up to N=40.Comment: 4 pages, including 2 figures, contribution to the Proceedings of
EP2DS-14, submitted to Physica
Singlet-triplet transitions in highly correlated nanowire quantum dots
We consider a quantum dot embedded in a three-dimensional nanowire with
tunable aspect ratio a. A configuration interaction theory is developed to
calculate the energy spectra of the finite 1D quantum dot systems charged with
two electrons in the presence of magnetic fields B along the wire axis.
Fruitful singlet-triplet transition behaviors are revealed and explained in
terms of the competing exchange interaction, correlation interaction, and spin
Zeeman energy. In the high aspect ratio regime, the singlet-triplet transitions
are shown designable by tuning the parameters a and B. The transitions also
manifest the highly correlated nature of long nanowire quantum dots.Comment: 4 pages, 4 figure
Configuration interaction method for Fock-Darwin states
We present a configuration interaction method optimized for Fock-Darwin
states of two-dimensional quantum dots with an axially symmetric, parabolic
confinement potential subject to a perpendicular magnetic field. The
optimization explicitly accounts for geometrical and dynamical symmetries of
the Fock-Darwin single-particle states and for many-particle symmetries
associated with the center-of-mass motion and with the total spin. This results
in a basis set of reduced size and improved accuracy. The numerical results
compare well with the quantum Monte Carlo and stochastic variational methods.
The method is illustrated by the evolution of a strongly correlated
few-electron droplet in a magnetic field in the regime of the fractional
quantum Hall effect.Comment: 17 pages, 3 figures, ReVTeX4, submitted to Solid State Communication
The Collapse of the Spin-Singlet Phase in Quantum Dots
We present experimental and theoretical results on a new regime in quantum
dots in which the filling factor 2 singlet state is replaced by new spin
polarized phases. We make use of spin blockade spectroscopy to identify the
transition to this new regime as a function of the number of electrons. The key
experimental observation is a reversal of the phase in the systematic
oscillation of the amplitude of Coulomb blockade peaks as the number of
electrons is increased above a critical number. It is found theoretically that
correlations are crucial to the existence of the new phases.Comment: REVTeX4, 4 pages, 4 figures, to appear in PR
Exchange-correlation energy densities for two-dimensional systems from quantum dot ground-states
In this paper we present a new approach how to extract polarization-dependent
exchange-correlation energy densities for two-dimensional systems from
reference densities and energies of quantum dots provided by exact
diagonalization. Compared with results from literature we find systematic
corrections for all polarizations in the regime of high densities.Comment: 7 figures. submitted to Phys. Rev.
Higher Landau levels contribution to the energy of interacting electrons in a quantum dot
Properly regularized second-order degenerate perturbation theory is applied
to compute the contribution of higher Landau levels to the low-energy spectrum
of interacting electrons in a disk-shaped quantum dot. At ``filling factor''
near 1/2, this contribution proves to be larger than energy differences between
states with different spin polarizations. After checking convergence of the
method in small systems, we show results for a 12-electron quantum dot, a
system which is hardly tractable by means of exact diagonalization techniques.Comment: 4 pages, 4 figure
Exchange-correlation vector potentials and vorticity-dependent exchange-correlation energy densities in two-dimensional systems
We present a new approach how to calculate the scalar exchange-correlation
potentials and the vector exchange-correlation potentials from current-carrying
ground states of two-dimensional quantum dots. From these exchange-correlation
potentials we derive exchange-correlation energy densities and examine their
vorticity (or current) dependence. Compared with parameterizations of
current-induced effects in literature we find an increased significance of
corrections due to paramagnetic current densities.Comment: 5 figures, submitted to PR
Electronic Correlations in Double Quantum Dots
We present a study of the electronic structure of two laterally coupled
gaussian quantum dots filled with two particles. The exact diagonalization
method has been used in order to inspect the spatial correlations and examine
the particular spin singlet-triplet configurations for different coupling
degrees between quantum dots. The outcome of our research shows this structure
to have highly modifiable properties promoting it as an interesting quantum
device, showing the possible use of this states as a quantum bit gate.Comment: 4 pages, 4 figures, REVTeX
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