2,132 research outputs found
Radius dependent shift of surface plasmon frequency in large metallic nanospheres: theory and experiment
Theoretical description of oscillations of electron liquid in large metallic
nanospheres (with radius of few tens nm) is formulated within
random-phase-approximation semiclassical scheme. Spectrum of plasmons is
determined including both surface and volume type excitations. It is
demonstrated that only surface plasmons of dipole type can be excited by
homogeneous dynamical electric field. The Lorentz friction due to irradiation
of electro-magnetic wave by plasmon oscillations is analyzed with respect to
the sphere dimension. The resulting shift of resonance frequency turns out to
be strongly sensitive to the sphere radius. The form of e-m response of the
system of metallic nanospheres embedded in the dielectric medium is found. The
theoretical predictions are verified by a measurement of extinction of light
due to plasmon excitations in nanosphere colloidal water solutions, for Au and
Ag metallic components with radius from 10 to 75 nm. Theoretical predictions
and experiments clearly agree in the positions of surface plasmon resonances
and in an emergence of the first volume plasmon resonance in the e-m response
of the system for limiting big nanosphere radii, when dipole approximation is
not exact
Correlation between electrons and vortices in quantum dots
Exact many-body wave functions for quantum dots containing up to four
interacting electrons are computed and we investigated the distribution of the
wave function nodes, also called vortices. For this purpose, we evaluate the
reduced wave function by fixing the positions of all but one electron and
determine the locations of its zeros. We find that the zeros are strongly
correlated with respect to each other and with respect to the position of the
electrons and formulate rules describing their distribution. No multiple zeros
are found, i.e. vortices with vorticity larger than one. Our exact calculations
are compared to results extracted from the recently proposed rotating electron
molecule (REM) wave functions
Emission spectrum of quasi-resonant laterally coupled quantum dots
We calculate the emission spectrum of neutral and charged excitons in a pair
of laterally coupled InGaAs quantum dots with nearly degenerate energy levels.
As the interdot distance decreases, a number of changes take place in the
emission spectrum which can be used as indications of molecular coupling. These
signatures ensue from the stronger tunnel-coupling of trions as compared to
that of neutral excitons.Comment: 7 pages, 7 figure
The Future of Quark Matter at RHIC
Projected annual results for heavy particle and high-p_{T} correlation
studies at future RHICII luminosities.Comment: 8 pages, 3 figures. Proceedings for Quark Matter 2006, Shanghai,
Chin
Chiral Spin Textures of Strongly Interacting Particles in Quantum Dots
We probe for statistical and Coulomb induced spin textures among the
low-lying states of repulsively-interacting particles confined to potentials
that are both rotationally and time-reversal invariant. In particular, we focus
on two-dimensional quantum dots and employ configuration-interaction techniques
to directly compute the correlated many-body eigenstates of the system. We
produce spatial maps of the single-particle charge and spin density and verify
the annular structure of the charge density and the rotational invariance of
the spin field. We further compute two-point spin correlations to determine the
correlated structure of a single component of the spin vector field. In
addition, we compute three-point spin correlation functions to uncover chiral
structures. We present evidence for both chiral and quasi-topological spin
textures within energetically degenerate subspaces in the three- and
four-particle system.Comment: 13 pages, 17 figures, 1 tabl
Structural properties of electrons in quantum dots in high magnetic fields: Crystalline character of cusp states and excitation spectra
The crystalline or liquid character of the downward cusp states in N-electron
parabolic quantum dots (QD's) at high magnetic fields is investigated using
conditional probability distributions obtained from exact diagonalization.
These states are of crystalline character for fractional fillings covering both
low and high values, unlike the liquid Jastrow-Laughlin wave functions, but in
remarkable agreement with the rotating-Wigner-molecule ones [Phys. Rev. B 66,
115315 (2002)]. The crystalline arrangement consists of concentric polygonal
rings that rotate independently of each other, with the electrons on each ring
rotating coherently. We show that the rotation stabilizes the Wigner molecule
relative to the static one defined by the broken-symmetry
unrestricted-Hartree-Fock solution. We discuss the non-rigid behavior of the
rotating Wigner molecule and pertinent features of the excitation spectrum,
including the occurrence of a gap between the ground and first excited states
that underlies the incompressibility of the system. This leads us to conjecture
that the rotating crystal (and not the static one) remains the relevant ground
state for low fractional fillings even at the thermodynamic limit.Comment: Published version. Typos corrected. REVTEX4. 10 pages with 8
postscript figures (5 in color). For related papers, see
http://www.prism.gatech.edu/~ph274cy
Creating excitonic entanglement in quantum dots through the optical Stark effect
We show that two initially non-resonant quantum dots may be brought into
resonance by the application of a single detuned laser. This allows for control
of the inter-dot interactions and the generation of highly entangled excitonic
states on the picosecond timescale. Along with arbitrary single qubit
manipulations, this system would be sufficient for the demonstration of a
prototype excitonic quantum computer.Comment: 4 pages, 3 figures; published version, figure 3 improved, corrections
to RWA derive
On modeling of plasmon-induced enhancement of the efficiency of solar cells modified by metallic nano-particles
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