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Wavelength conversion in coupled quantum wells driven by terahertz fields has been studied using a model that includes the effects of band structure, excitons and intersubband transitions. Good agreement is achieved with published experimental data.
The photocurrents of carbon-nanotube field-effect transistors are small due to the small exciton ionization rate and large exciton nonradiative-decay rate, and the photocurrent gain is small for the long-channel devices.
Narrowband THz radiation drives transitions between bound electron states in GaAs neutral donors. Elastic light scattering from a donor bound exciton resonance allows time-resolved measurements of the excited state lifetime and THz-induced AC Stark effect.
We investigate collective electronic excitations for ultracold atoms in an optical lattice prepared in the Mott insulator phase. Frenkel like-excitons in these artificial crystals can appear when the atomic excited state line width is smaller than the exciton band width. When the optical lattice atoms are placed within a cavity the excitons and the cavity photons get coupled, and in the strong coupling...
We study theoretically the interactions of excitonic states with surface electromagnetic modes of a single-walled carbon nanotube. We show that these interactions result in the exciton-plasmon coupling that is significant in its strength due to the presence of weakly-dispersive low-energy (~0.5-2 eV) interband surface plasmon modes and large exciton excitation energies ~1 eV in small-diameter nanotubes...
We report on the coherent coupling between surface plasmon polaritons and quantum well excitons in a hybrid metal-semiconductor nanostructure. The coupling is probed by angle-resolved low temperature spectroscopy and analyzed within a coupled oscillator model.
Using time resolved optical spectroscopy we show that by angle tuning dispersive plasmon modes of metal disc arrays into resonance with emission of adjacent semiconductor nanocrystals we achieve five fold enhancement of radiative transition rates.
We investigate polaritons resulting from excitons localized in arrays with energy and oscillator strength fluctuations embedded in microcavities. The polariton emission shape remains robust under oscillator strength fluctuations, but is more sensitive to energy fluctuations.
We investigate the first and second order coherence of exciton-polariton condensates both in coordinate and momentum space. The measured correlations provide insights into the phase and intensity fluctuations induced by polariton interactions.
Decoherence between exciton states is compared with their decoherence with the ground state of a semiconductor in the presence of an electron-hole plasma. Non-equilibrium Green functions are used for deriving dynamical equations.
We have performed low-temperature micro-photoluminescence studies on individual single-walled carbon nanotubes in magnetic fields up to 5 T and directly measured the dark-bright exciton splitting magnitude through the observation of magnetic brightening.
Raman coherence between heavy-hole and light-hole excitons in quantum wells is isolated in an alternative spectrum and contributions from single exciton and correlated two-exciton states are studied experimentally and theoretically by excitation with different polarizations.
We present studies of 2D indirect excitons in an in-plane trap created by a laterally modulated gate voltage. Our data indicates an effective evaporative cooling of excitons in the elevated trap regime. We also observed narrow PL lines which correspond to the emission of localized and delocalized states of the indirect excitons in the trap. The homogeneous line broadening due to interaction increases...
We tune the exchange interaction in nanocrystals by manipulating the electron-hole wavefunction overlap under external electric fields and simultaneously probe the electronic structure and rich transient dynamics under strong magnetic fields (8 T).
We report on the kinetics of a low-temperature gas of indirect excitons in an optically-induced exciton trap. The loading time of excitons to the trap center is ~40 ns.
Using a two-color, three-pulse differential transmission technique, we manipulate nonlinear optical processes of electron spins in a modulation-doped CdTe quantum well through exciton injection. The spin manipulation takes place without optical spin rotation.
We demonstrated laser action in the regime of linear recombination of singlet excitons in para-sexiphenyl crystalline films in the form of nanofibers under optical excitation with femto- and nanosecond pulses.
We report spontaneous buildup of inphase (dasiazero-statepsila) and antiphase (dasiapi-statepsila) states in an exciton-polariton condensate array connected by weak periodic potential barriers. These states reflect the band structure and dynamic characteristics of array exciton-polariton condensates.
The lifetime and the Auger coefficient for 1s paraexctons in Cu2O from 5 K to 70 K was measured directly using excitonic Lyman spectroscopy. A possible experiment for realizing excitonic Bose-Einstein condensation is discussed.
The scintillation properties of a hydrothermal method grown ZnO crystal are evaluated for EUV laser excitation. The excitonic emission decay at 380-nm is determined to be 1.3-ns, almost identical to ultraviolet laser excitation cases.
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