| Titre : |
Control and transport of matter waves in an optical lattic |
| Type de document : |
these |
| Auteurs : |
Nathan Dupont, Auteur |
| Editeur : |
Toulouse : Université Paul Sabatier |
| Année de publication : |
2022 |
| Importance : |
212 P. |
| Langues : |
Anglais (eng) |
| Catégories : |
THESIS
|
| Index. décimale : |
THESIS |
| Résumé : |
The field of quantum simulation aims at emulating complex quantum systems on platforms that are easier to control and observe. In the last twenty years, ultracold atoms in optical lattices have established themselves as a versatile controllable system for quantum simulation. The three experimental studies presented in this manuscript take place in the development of this field. They are performed using Bose-Einstein condensates (BECs) in a one-dimensional optical lattice that can be precisely controlled in amplitude and phase. In the first study, we use the optimal control formalism to compute the way in which to continuously shift the lattice in order to arbitrarily shape the BEC distribution in the phase space of the system. We apply this method to different targets, among which squeezed Gaussian states more than four times narrower in position than the ground state of the system, as well as the ideal Floquet state superposition to perform quantum simulation of dynamical tunneling is the modulated lattice. The second study concerns the realization of a non-diffusive Hamiltonian ratchet. The ratchet effect consists in the emergence of a directed current of particles in a system with no net force. In this second work, we correlate the amplitude and phase modulations of the lattice to produce, in the phase space of the system, a region of non-chaotic trajectories that travels between lattice sites, resting periodically in the center of each sites. We experimentally implement this system and observe non-diffusive ratchet transport of matter waves in the optical lattice. Finally, we show how short-range interactions between atoms in the BECs lead to the emergence of a supercrystalline order in a sinusoidally modulated optical lattice for a modulation frequency coupling two energy levels. We develop a two-band tight-binding model which predicts that collisions occuring between the atoms of the BECs can lead to the growth of unstable Bogoliubov modes in the vicinity of avoided crossings in the quasi-energy spectrum of the modulated system. Interestingly, we experimentally demonstrate that the periodicity of the emergent order can be tuned through Floquet engineering of these crossings. |
| En ligne : |
https://theses.hal.science/tel-03997401v3 |
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Control and transport of matter waves in an optical lattic (2022)
