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Theses

BOSONS DE SPIN-1/2 ET 1 SUR RÉSEAUX OPTIQUES EN UNE ET DEUX DIMENSIONS

Abstract : Optical trapping of atoms on optical lattices allows the study of their behavior in the range of ultra low temperature, at the nanokelvin scale, without freezing their angular momentum degrees of freedom. Those recent trapping methods offer the possibility to analyse the quantum magnetism spontaneously adopted by the atoms. In this thesis we study numerically bosons with two internal effective degrees of freedom, referred to as spin-1/2 bosons, and also bosons with three degrees of freedom, spin-1 bosons, with two conceptually different methods: a simplified one using mean field approximation and an exact method, the Quantum Monte Carlo method. Beyond the study of these two systems, we compare a mean field method, sometimes excessively used, to the Quantum Monte Carlo method. The thorough investigation of the spin-1/2 bosons system in one and two dimensions in the zero temperature limit shows the influence of dimensionality on the physical properties of this system. The thermal effects, still present experimentally, are also analysed. Lastly, the spin-1 boson system trapped into a two dimensionnal lattice, a richer and more complicated system than the previous one, is investigated in the zero temperature limit. The study of these two systems reveals different magnetic organization in Mott insulators and superfluid phases, such as a ferromagnetic superfluid. First order phase transitions and coherent anticorrelated movements, present in the Mott phases, are also observed.
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Contributor : Laurent de Forges de Parny <>
Submitted on : Saturday, February 1, 2014 - 10:11:24 PM
Last modification on : Monday, October 12, 2020 - 10:28:24 AM
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  • HAL Id : tel-00940582, version 1

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Laurent de Forges de Parny. BOSONS DE SPIN-1/2 ET 1 SUR RÉSEAUX OPTIQUES EN UNE ET DEUX DIMENSIONS. Gaz Quantiques [cond-mat.quant-gas]. Université Nice Sophia Antipolis, 2012. Français. ⟨tel-00940582⟩

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