Étude expérimentale des forces de Casimir

Abstract : The study of density fluctuations inside confined liquid systems has received the attention of recent theoretical and experimental papers. In order to analyze the role of confinement on the statistical properties of fluctuations, we developed a highly sensitive system where the intensity of fluctuations, as well as their spatial correlation length can be simply tuned. The idea will be to enhance the role of fluctuations working close to the critical temperature Tc of a second order phase transition in a binary mixture. Indeed, the correlation length dramatically increases when one approaches the critical demixion point.The confinement is obtained by using a sphere-plane geometry with a colloidal particle attached to the cantilever of an Atomic Force Microscope (AFM). When the correlation length is comparable with the distance of confinement, Fisher and De Gennes predicted the existence of an interesting effect: the two surfaces will be submitted to either an attracting or a repelling force, depending on boundary conditions. This effect is called the critical Casimir force in reference to the quantum Casimir force resulting from the confinement of quantum fluctuations of the electromagnetic field.During this thesis, we measured the quantum Casimir force between the sphere and the plate, first in a nitrogen atmosphere and then in ethanol, showing that the developed instrument is sufficiently sensible to measure very weak force, of the same order of magnitude or even weaker than the critical Casimir force. Measurements are compared to Lifshitz theory, taking into account the finite conductivity of surfaces.
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https://tel.archives-ouvertes.fr/tel-01490037
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Submitted on : Tuesday, March 14, 2017 - 6:46:05 PM
Last modification on : Thursday, April 19, 2018 - 2:54:04 PM
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Anne Le Cunuder. Étude expérimentale des forces de Casimir. Physique [physics]. Université de Lyon, 2017. Français. ⟨NNT : 2017LYSEN007⟩. ⟨tel-01490037⟩

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