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Summary form only given. Correlated and entangled single photon states have made possible many fundamental studies in quantum optics such as the Bell-type test of hidden variables and non-locality, explorations of quantum interference properties, and investigations of quantum information processing and quantum communications technologies such as quantum cryptography, quantum computing, and quantum...
Summary form only given. Four-particle correlation mediated by the Coulomb interaction has been found to play a major role in the nonlinear optical response at the semiconductor band edge at low excitation density. The attractive interaction of the excitons with opposite spins result in the formation of bound (bi-exciton) and unbound (scattered) two-exciton states. In this paper we report on the first...
Summary form only given. Time-integrated (TI) and time-resolved (TR) four-wave-mixing (FWM) techniques have been employed successfully to study the relaxation dynamics of coherent excited states in semiconductors and semiconductor quantum wells. A large number of experimental and theoretical studies on FWM have been mainly focused on the resonant FWM signals in thin semiconductors with thicknesses...
Summary form only given. We present femtosecond time-resolved investigations of non-equilibrium coherent 1.0 phonon dynamics in CdS/sub 0.7/Se/sub 0.3/ quantum dots embedded in a glass matrix. The three-dimensional quantum confinement of the LO phonons has been demonstrated by means of linear Raman spectroscopy. For the electron and hole states the size of the microcrystallites is in the regime of...
Summary form only given. A microscopic many-body theory for the optical and electronic properties of semiconductors is reviewed with an emphasis on the role of correlation effects among the electronic excitations and in the light matter coupling. The nonlinear response near the fundamental absorption edge and the light emission characteristics are studied for a variety of laser excited heterostructure...
Summary form only given. As we have shown recently, measurement of the polarization-sensitive phase of the quantum beats in time-integrated four wave mixing (FWM) signal provides us with a novel and effective tool here. The amplitude and phase of the oscillating TI-FWM signal are determined by the interplay of the four-particle correlation and mean field mechanisms of the optical nonlinearity at the...
Summary form only given. Four-wave mixing processes in semiconductor quantum wells have been studied intensively for many years, because they allow for a detailed investigation of ultrafast many-body processes such as quantum correlations and quantum coherences. From a theoretical point of view one can roughly divide the existing approaches into two categories: (i) fully microscopic theories based...
Summary form only given. A unified description of nonlinear optical spectroscopies of molecular aggregates (starting with the Frenkel-Heitler-London Hamiltonian) and semiconductors (starting with the two-band model) is developed using the nonlinear exciton equations (NEE). The equations follow explicitly the complete set of dynamical (one-, two-, and three-point) exciton variables relevant for the...
Summary form only given. In a coherent control four-wave mixing (FWM) experiment, a first pulse, 1, can excite a certain electron-hole pair density n/sub eh/ in a semiconductor. Because this density is connected with interband coherence, a second phase locked and time-delayed pulse, 1', adjusted for destructive interference, can lead to a coherent reemission of photons. As a result, a first light...
Summary form only given. Recently, non-degenerate inter-level interactions caused by Coulomb correlations have been studied by using partially non-degenerate four-wave mixing. The most important signature of this interaction was the existence of strong coherent emission at the exciton resonance even when the first pulse (/spl omega//sub 1/) excites continuum that is non overlapping to the exciton...
Summary form only given. Coherent dynamics in semiconductors can be strongly affected by interaction between energetically degenerate interband transitions. In this paper, we demonstrate for the first time to our knowledge that this strong interaction can be used to transfer the coherence properties of discrete excitons to continuum transitions and vice versa. This transfer can generate coherent radiation...
Summary form only given. Two-beam coupling (TBC) with chirped pulses can be used to determine response times shorter than the chirped pulse duration. Here we explore the possibility of a direct determination of the electronic response time through measurements of two-beam coupling with pulses as short as 10 fs. We use fused silica as a model system. In numerical simulations we assume that the pulses...
Summary form only given. When intense TW-fs-laser pulses propagate through the atmosphere, nonlinear effects like self-phase modulation (SPM), self-focusing (SF) or degenerated four-wave mixing (DFWM) cause an immense change of the temporal and spatial profile. The frequency content is changed, too. Depending on the initial beam profile, the pulse duration and other parameters like temporal chirp,...
Summary form only given. We present the first investigation of electronic dephasing in the presence of two dimensional electron gas (2DEG) in the Quantum Hall regime using four wave mixing (FWM). We observe a transition from Markovian to non-Markovian behavior and abrupt variation of the decay time with filling factor, which we interpret in terms of photoexcited electrons scattering with collective...
Summary form only given. The nonlinear optical response in semiconductors has traditionally been treated in a mean field approximation at the 2-particle level. Recent work, in particular comparisons of four-wave mixing (FWM) with microscopic theory, have demonstrated the importance of 4-particle correlations. Such experiments, however, are not optimally sensitive to correlations at the 6-particle...
Summary form only given. We present experimental results on the transfer of the orbital angular momentum of light to a system of cold cesium atoms. A four-wave-mixing process was used as an indirect tool to observe this transfer. We have observed the transfer of optical angular momentum (OAM) of light from an optical beam to the system of cold cesium atoms. We use the non-degenerate four-wave mixing...
Summary form only given. We present transient amplitude and spin grating measurements in room temperature InGaAsP multiple quantum wells (MQWs) for the first time using picosecond laser pulses at 1.525 microns. We deduce in-well diffusion coefficients and compare these with those previously reported for GaAs.
Summary form only given. Since the pioneering experimental results of optical vortex solitons have been in the centre of interest because of their fundamental importance in optics and other fields of physics, and because of their potential applications for all-optical information processing. Formally conventional vortex solitons exist on an infinite nonzero background, which in practice requires rather...
Summary form only given. We report on the observation of four wave mixing (FWM) in a sample of cold cesium atoms in a magneto optical trap (MOT), where the trapping beams also play the role of the dressing field. The trapping and the FWM beams are provided by a stabilized Ti:sapphire laser. However, the FWM beams have the same linear polarization in contrast with the opposite circular polarizations...
Summary form only given. The strong coupling between quantum well exciton and cavity photon leads to the so-called microcavity polaritons whose energy dispersion is very sharp due to the photon component. Unlike bare excitons, the optical response of polaritons is very sensitive to the incidence angle of the exciting laser beams. This means that the dispersive character can drastically affect nonlinear...
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