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Fluides quantiques de lumière avec des vapeurs atomiques chaudes

Abstract : In this thesis, we are interested in the propagation of a laser beam through a rubidium hot atomic vapour. Due to the Kerr-like non-linearity of the medium, the light will present, during its evolution in the vapour, a behaviour that can be described by the non-linear Schrödinger equation (or Gross-Pitaevskii equation) which is equivalent to hydrodynamical equations in the transverse plane of propagation. We can then observe various light behaviours identical to the ones we see in the case of matter waves such as for liquids or gas: we talk about quantum fluid of light.To study such phenomena, calibration of our medium non-linearity is necessary. Non-linear properties of hot atomic vapours being on various parameters experimentally accessible such as atomic density, laser intensity or detuning, it allows us true flexibility. Following these calibrations, the study of 2D dispersive shockwaves starts. Helped by a numerical study, we show the existence of additional phenomena such as non-locality, absorption or saturation of the non-linearity, missing effects in the initial theoretical model. A quantitative study is then carried out on these different phenomena showing surprisingly high values of non-locality (until 100 µm) and, counter-intuitively, the positive impact of the dissipation on our system.Finally, in a second project, the study of vortex behavior is done from their creation via dark soliton decay to their interactions and annihilations. An adapted imaging system allows us to make an in situ and real-time observation of the wave front (intensity and phase) at the end of the propagation, giving us access to information such as the density and velocity of our fluid of light. Work is also done on initial conditions allowing us to accelerate the decay process for vortex creation by adding initial velocity to the fluid and even cause collisions by choosing specific orientations of these velocities. Another method we developed (relative phase scan) offers us the possibility to work in much better stability conditions, allowing us to consider our photons in a hydrodynamic regime with a better approximation.
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Submitted on : Friday, November 12, 2021 - 10:15:29 AM
Last modification on : Tuesday, January 4, 2022 - 6:35:56 AM


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  • HAL Id : tel-03426248, version 1



Pierre Azam. Fluides quantiques de lumière avec des vapeurs atomiques chaudes. Physique Quantique [quant-ph]. Université Côte d'Azur, 2021. Français. ⟨NNT : 2021COAZ4059⟩. ⟨tel-03426248⟩



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