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Décohérence, symétries et relaxation de spin dans les boites quantiques de semiconducteurs.

Abstract : We investigate, by means of optical spectroscopy of a single InAs/GaAs quantum dot, the neutral exciton decoherence inside the dot, its fine structure and its spin relaxation.
We show that the coherence is intrinsically limited by a non-perturbative coupling to acoustic phonons, and extrinsically limited by the presence of a fluctuating electrostatic environment around the dots.
We observe that the fine structure depends on the dots local density, which influences their geometry as their strain profile, and analyse, in low density regions, original dots emitting a strongly polarized light.
We study the exciton spin relaxation by measuring the polarisation ratio of the emission. On an ensemble of dots, we measure a relaxation time of 10 ns at 10 K and show that the relaxation dynamics is extremely sensitive to the dots environment. On a single dot, we show that the spin can relax very quickly (in 100 ps), even at 10 K.
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https://tel.archives-ouvertes.fr/tel-00011133
Contributor : Ivan Favero <>
Submitted on : Wednesday, November 30, 2005 - 10:51:55 AM
Last modification on : Thursday, December 10, 2020 - 12:36:52 PM
Long-term archiving on: : Friday, September 14, 2012 - 4:10:12 PM

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  • HAL Id : tel-00011133, version 1

Citation

Ivan Favero. Décohérence, symétries et relaxation de spin dans les boites quantiques de semiconducteurs.. Physique [physics]. Université Pierre et Marie Curie - Paris VI, 2005. Français. ⟨tel-00011133⟩

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