Cumulant theory of the unitary Bose gas: Prethermal and Efimovian dynamics

V. E. Colussi (Corresponding author), H. Kurkjian, M. Van Regemortel, S. Musolino, J. van de Kraats, S. J. J. M. F. Kokkelmans

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We study the quench of a degenerate ultracold Bose gas to the unitary regime, where interactions are as strong as allowed by quantum mechanics. We lay the foundation of a cumulant theory able to simultaneously capture the three-body Efimov effect and ergodic evolution. After an initial period of rapid quantum depletion, a universal prethermal stage is established, characterized by a kinetic temperature and an emergent Bogoliubov dispersion law, while the microscopic degrees of freedom remain far from equilibrium. Integrability is then broken by higher-order interaction terms in the many-body Hamiltonian, leading to a momentum-dependent departure from power law to decaying exponential behavior of the occupation numbers at large momentum. We also find signatures of the Efimov effect in the many-body dynamics and make a precise identification between the observed beating phenomenon and the binding energy of an Efimov trimer. Throughout the paper, our predictions for a uniform gas are quantitatively compared with experimental results for quenched unitary Bose gases in uniform potentials.
Original languageEnglish
Article number063314
Number of pages29
JournalPhysical Review A
Issue number6
Publication statusPublished - 11 Dec 2020


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