Quantum correlations of momenta in interacting atomic Bose gases
David Clément(Institut d’Optique, Univ. Pais-Saclay)
| Quand ? |
Le 16/05/2022, de 11:00 à 12:00 |
|---|---|
| Où ? | Amphi Sciences de la Matière |
| Participants |
David Clément |
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A cornerstone in the description of quantum fluids is Bogoliubov's theory, which provides a physical framework explaining how superfluidity emerges from interactions in ensembles of weakly-interacting bosons. At the microscopic level, it predicts that interactions deplete the condensate by promoting pairs of bosons with opposite momenta outside the condensate, the quantum depletion. Exploiting the capability to detect individual metastable Helium atoms after a long free expansion, we confirmed this microscopic prediction experimentally. I shall present the measurements performed to reveal Bogoliubov's pairs, a manifestation of interaction-induced quantum fluctuations at equilibrium, and their properties.
While Bogoliubov's theory was introduced in the context of superfluid liquid Helium, interactions in liquid Helium deplete too strongly the condensate for Bogoliubov's theory to be applicable. This naturally raises the question of the fate of the Bogoliubov's pairs in a regime of strong depletion of the condensate. Varying the optical landscape where metastable Helium atoms are held, we have studied how the pairing signal changes as interactions increase and the gas become more correlated. I shall discuss this recent results, as well as on-going efforts to observe atom triplets and quadruplets, in addition to atom pairs.