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Correlations in low-dimensional quantum gases

Abstract : Ultracold atom gases are a versatile platform to simulate condensed matter physics phenomena, as virtually any parameter is experimentally tunable with a high accuracy.In particular, highly anisotropic traps allow the realization of low-dimensional systems, where the role of quantum fluctuations is enhanced. I investigate the paradigmatic model of a one-dimensional Bose gas with contact interactions, a.k.a the Lieb-Liniger model, using powerful analytical tools such as Bethe Ansatz, Conformal Field Theory and the Tomonaga-Luttinger liquid formalism, as well as the Bose-Fermi mapping.These exact and approximate methods allow me to investigate with high accuracy its Ground-State energy and thermodynamics, excitation spectra and correlation functions, from the k-body local correlations to the momentum distribution and the dynamical structure factor. These quantities yield useful informations on the coherence and superfluidity of a gas. In particular, I study the drag force exerted by a gaussian laser beam stirred into the gas in linear response theory.Then, releasing a transverse trapping, I study the appearance of a multimode structure and the dimensional crossover. All along, the effect of a harmonic trap in the longitudinal direction is studied within the Local Density Approximation.
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Submitted on : Thursday, April 5, 2018 - 12:03:08 PM
Last modification on : Tuesday, October 6, 2020 - 4:28:40 PM

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  • HAL Id : tel-01759278, version 1

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Guillaume Lang. Correlations in low-dimensional quantum gases. Quantum Gases [cond-mat.quant-gas]. Université Grenoble Alpes, 2017. English. ⟨NNT : 2017GREAY076⟩. ⟨tel-01759278⟩

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