11 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
Quantum Dots - Theory for Experiments
A simple model based on the effective-mass method and treating a quantum dot as a small irregularity of the periodic crystal field is developed and used for the description of the radiative recombination of an exciton captured in that quasi-zero-dimensional structure. The additional peaks appearing in the photoluminescence spectra at the critical quantum dot size are predicted as a consequence of the metastable excited states occurring in the energy spectrum of a confined exciton. The obtained dependence of the photoluminescence spectrum on the dot size and magnetic field reproduces well the available experimental results
Coherent and incoherent phonon processes in artificial atoms
Carrier–phonon interaction in semiconductor quantum dots
leads to three classes of phenomena: coherent effects (spectrum
reconstruction) due to the nearly-dispersionless LO phonons,
incoherent effects (transitions) induced by acoustical phonons and
dressing phenomena, related to non-adiabatic, sub-picosecond excitation.
Polaron
spectra, relaxation times and dressing-related decoherence rates are
calculated, in accordance with experiment
Model of Qubit in Multi-Electron Quantum Dot
The discussion of qubit for quantum computation in quantum dots technology is presented. The state-of-the-art structure of multi-electron dot is considered and the appropriate quasi-two-level system is suggested employing the singlet-triplet transition in the presence of magnetic field. The methods of qubit rotation (the write procedure) as well as two-qubit operations, as controlled-NOT, in vertically stacked dots system are analysed
Model of Qubit in Multi-Electron Quantum Dot
The discussion of qubit for quantum computation in quantum dots technology is presented. The state-of-the-art structure of multi-electron dot is considered and the appropriate quasi-two-level system is suggested employing the singlet-triplet transition in the presence of magnetic field. The methods of qubit rotation (the write procedure) as well as two-qubit operations, as controlled-NOT, in vertically stacked dots system are analysed