Séminaire des doctorants : Jan-Philipp BUREIK

Séminaire des doctorants donné par Jan-Philipp BUREIK du groupe Gaz quantiques, le 28 avril 2022 à 13h15 dans l'auditorium de l'Institut d'Optique à Palaiseau, sur le thème : " Full counting statistics of interacting quantum gases after an expansion. "

Résumé : " We study the full counting statistics (FCS) in interacting quantum gases detected atom-by-atom after a free-fall expansion. In the small far-field volumes we consider, the FCS reveals the many- body coherence properties of the gas. We characterise two iconic states of interacting lattice bosons, Mott insulators and Bose superfluids, through their counting statistics and n-body correlations up to n = 6 atoms. Unity-filled Mott insulators exhibit a thermal FCS and perfectly-contrasted amplitudes g(n)(0) ≃ n!. In weakly-interacting Bose superfluids, the FCS measured close to the momentum k = 0 is well described by the Poisson statistics expected for a pure condensate. How- ever, we observe small deviations to a coherent state, g(n)(0) > 1, at high orders of correlations. Furthermore, these deviations become larger as superfluids become more correlated upon increasing the interactions. Finally, we introduce a simple model that incorporates the contribution from the depletion of the condensate, and whose predictions are compatible with our observations over a large range of interaction strengths. "