1,721,004 research outputs found
Excitonic and biexcitonic states in semiconductor quantum dots
No full textWe analyze excitonic and biexcitonic effects in the coherent optical spectra of semiconductor quantum dots using a density-matrix approach, that explicitly accounts for exciton-exciton interactions. A consistent description of additional peaks appearing at higher photoexcitation density is given
Excitonic and biexcitonic effects in the coherent optical response of semiconductor quantum dots
No full textFew particle effects in the coherent optical spectra of semiconductor quantum dots are analyzed using a density-matrix approach that explicitly accounts for exciton-exciton interactions. Few-particle interactions are shown to play an important role in the appearance of additional lines with increasing pumping density. The nature of these interactions is examined within the framework of biexcitonic interactions. A consistent description of additional peaks appearing at high photoexcitation density is given
Self-induced transparency in semiconductor quantum dots
No full textWe present a theoretical analysis of self-induced transparency in a sample of inhomogeneously broadened semiconductor quantum dots. A general theoretical framework accounting for mutual light-matter interactions in the presence of single and biexciton transitions is presented. Numerical results demonstrate that intense light pulses can propagate in realistic state-of-the-art dot samples without suffering strong losses
Excitonic and biexcitonic effects in the coherent optical response of semiconductor quantum dots
No full textWe analyze few-particle effects in the coherent optical spectra of semiconductor quantum dots using a density-matrix approach that explicitly accounts for exciton-exciton interactions. A consistent description of additional peaks appearing at high photoexcitation density is given. (C) 1999 Elsevier Science B.V. All rights reserved
Exploiting exciton-exciton interactions in semiconductor quantum dots for quantum-information processing
No full textWe propose an all-optical implementation of quantum-information processing in semiconductor quantum dots, when electron-hole excitations (excitons) serve as the computational degrees of freedom (qubits). We show that the strong dot confinement leads to an overall enhancement of Coulomb correlations and to a strong renormalization of the excitonic states, which can be exploited for performing conditional and unconditional qubit operations
Optical near-field mapping of bright and dark quantum dot states
No full textWe theoretically investigate scanning nearfield optical microscopy (SNOM) of semiconductor quantum dots. In the nearfield regime bright and dark excitonic states become mixed, opening new channels for the coupling to the electromagnetic field. As a consequence, ultra-narrow luminescence lines appear in the spectra, corresponding to very long lived excitonic states. © 2007 American Institute of Physics
Theoretical analysis of the optical spectra of InxGa1-xN quantum dots in InyGa1-yN layers
No full textA theoretical investigation of the optical properties of InxGa1-N-x quantum dots in InyGa1-y N layers is presented. We compute the single-particle energies and wave functions for different dot dimension and indium composition in the alloys, and use them to predict optical properties. The results allow us to identify signatures of quantum confinement characterizing the optical spectra. (C) 2000 Elsevier Science B.V. All rights reserved
Optical spectra of nitride quantum dots: Quantum confinement and electron-hole coupling
Full text linkWe calculate the optical properties of nitride-based quantum dots by taking into account quantum confinement as well as electron-hole interaction. We analyze model structures simulating In_xGa_{1−x}N dots in In_yGa_{1−y}N layers with different alloy compositions. We discuss the trends with the dot size and show that quantum confined excitations exist for a broad range of sizes down to the smallest observed dots. Our results allow us to identify the strong role of Coulomb correlations in the optical spectra and to predict a strong influence of photoexcitation power on selection rules in polarized samples. The signature of quantum confinement can be utilized for a critical interpretation of measured optical spectra
Theoretical analysis of the optical spectra of InGaN quantum dots in InGaN layers
No full textA theoretical investigation of the optical properties of In_xGa_{1-x}N quantum dots in In_{y}Ga_{1-y}N layers is presented. We compute the single-particle energies and wave functions for different dot dimension and indium composition in the alloys, and use them to predict optical properties. The results allow us to identify signatures of quantum confinement characterizing the optical spectra
Local absorption spectra of single and coupled semiconductor quantum dots
No full textWe study theoretically the local absorption spectra of single and double semiconductor quantum dots (QDs). in the linear regime. The three-dimensional confinement leads to an enhancement of the Coulomb correlations, while the spectra depend crucially on the size of the 'local' probe. We show that because of such Coulomb correlations the intensity of certain optical peaks as a function of the resolution can exhibit an unexpected non-monotonic behavior for spatial resolutions comparable with the excitonic Bohr radius. We finally discuss the optical near-field properties of coupled QDs for different coupling strengths. (C) 2001 Elsevier Science B.V. All rights reserved
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